Anonymous
01-21-2003, 11:47 PM
Irish Wake
normal member in standard member. 1. Mufflers on 26' Shamrock
Does anyone have mufflers installed on their 26' Shamrock? If so, what brand, type and how are they mounted. The bilge is very tight and I can't see how it can be done.
Regards
Randy
Date: 05:00 p.m. on 03-08-2001
Leprechaun
premium member in standard member. 2. Re:Mufflers on 26' Shamrock
Randy - I just spent 30 minutes on another site trying to locate a response to this question I wrote last year, couldn't find it, so I'll try to keep it brief here. Right.
O.k. - so here's my take on this muffler question. IMHO no small inboard boat should ever have a pair of those hard-rubber nitrile or worse, fiberglas mufflers below the deck. If you are going to put a set on her, you need metal. Let me 'splain why. Many people are unaware that the exhaust hose in their boats is actually rated to withstand higher heat levels than the rubber or glass mufflers they are connected too. Don't believe me? Check into it. So what does this mean? It means that in the unfortunate event of losing a riser to clogging offshore, the hose will last far longer than the muffler, the muffler will melt, hole and sink the boat. No bull. Proven fact. As you are probably aware, the exhaust system of a Shamrock is actually below the waterline. Always full of water. So a hole ANYWHERE south of the risers will cause some tense moments, if not total panic. No bilge pumps we could employ in these boats could possibly keep up with the flow a hole the size of a silver dollar would produce. Glug, glug, down she goes. A good friend actually witnessed a 35' Lobsterboat off Mountauk, L.I. lose a riser, hole his rubber muffler and if it weren't for a couple of gas-powered pumps that the Coasties heli-lifted to the boat, she was a gonner for sure. Makes you kinda re-think the whole "My boat is too loud for my wife" thing.
So what's a guy to do? Allow me to introduce you to "Freddie's Famous Copper Shamrock Exhaust." And this is how you make it yourself. I will use my Predator 26 as an example as I was there during fabrication/installation. First - go to your local plumbing supply store and order an 8' length of "Schedule M" Copper pipe in the correct diameter. In my case that was 3", but in a 20' or 22' Shammie it could very well be 2 or 2.5" exhaust hose and hence, pipe. DO NOT allow the supply house to sell you that cheap-ass thin regular plumbing pipe. It will work for a while, but who knows? Get M grade. They might have to special order it, it took 2 days to get mine. Now cut that 8' length in half. This will give you, obviously 2 4' sections which will be your mufflers. Now on my rig, we installed no baffling, so its a little bit louder than the other boats Freddie's done, but with my exhaust exiting under my swim platform the sound is thrown down away from the cockpit and we can actually conduct normal conversation at the helm while underway.
If you want to install sound-cancelling baffles what you need to do is get more copper - here the cheap thin stuff will work. Cut off a piece of the other pipe around 6" long and then cut that piece again inorder to get a flat piece after banging it flat. Now what you are gonna do is make inserts, which will resemble a half-moon that we will be installing in the muffler pipe. They need to be round on one side and straight across on the other and be exactly 1.5" diameter. They will obviously inhibit flow in exactly 50% of the inside of the pipe. Take the original pipe and exactly 1 foot from the end, make a slot cut 1/2 way thru and take the baffle and braise it into the slot using copper rod for the braising material. Now go to the other end of the pipe and 180-degrees OPPOSITE to first baffle location, cut a second slot 12" in and braise in the second baffle. That's really it. Not complicated, but damned effective and impervious to deterioration or worse to failure due to heat. Now if you want to get fancy (Like I did) you can braise two bronze bolts to each of the pipes and tie them into your hull ground/bonding system. As far as securing them to the boat - I ran them down both longitudinal bulkheads, on either side of the cockpit belly box, and used a few strips of copper as straps to secure them. Try not to use real long screws here, the fuel tanks are real close to the other side of the bulkheads.
I told you I would keep it brief, didn't I? Rgds, Leprechaun
Date: 08:59 p.m. on 03-08-2001
Irish Wake
3. Re:Re:Mufflers on 26' Shamrock
Lep, A couple of followups, does copper have a higher heat rating then fiberglass? I have fiberglass exhaust from the exhaust elbow back to the thru hulls. Does the half moon baffles restrict the flow of water through the exhuast and therefore does it cause excessive back pressure? Also, would rubber exhuast hose all the way from the riser elbows to the thru hulls quiet things down? Why can't I just put those half moon baffles in the fiberglass exhaust pipes that are already installed? Let me know what you think
Regards
Randy
Date: 12:32 p.m. on 03-09-2001
Leprechaun
premium member in standard member. 4. Re:Mufflers on 26' Shamrock
Randy - I don't really understand your first question. Are you asking if Copper pipe can resist heat better than fiberglas? If that's the question, then yes, of course, is the answer. Regarding having fiberglass tubes from the exhaust riser to the transom, I would change that immediately, see my reasons above. The half-moon baffles have no effect we can observe on the engine's performance, same part-throttle response and gph fuel burn and exactly the same top end speed and rpms, just 1/2 the noise.
As far as using rubber exhaust hose all the way from the risers to the transom, two problems there. First, I believe this is prohibited by the American Boat Council, runs of rubber pipe are supposted to be 2' or less, so I am told. Secondly, the problem with long runs of rubber hose is that it tends to "Breathe" in and out with exhaust pulses, setting up a weird rpm-related vibration at certain engine speeds that will drive you nuts trying to track down. As far as inserting baffles in your existing fiberglass pipe, see my feeling above about fiberglass exhausts. Don't throw good efforts after bad. Rgds, Leprechaun
Date: 06:04 p.m. on 03-09-2001
Irish Wake
5. Re:Re:Mufflers on 26' Shamrock
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Leprechaun (03-09-2001 06:04 p.m.):
Randy - I don't really understand your first question. Are you asking if Copper pipe can resist heat better than fiberglas? If that's the question, then yes, of course, is the answer. Regarding having fiberglass tubes from the exhaust riser to the transom, I would change that immediately, see my reasons above. The half-moon baffles have no effect we can observe on the engine's performance, same part-throttle response and gph fuel burn and exactly the same top end speed and rpms, just 1/2 the noise.
As far as using rubber exhaust hose all the way from the risers to the transom, two problems there. First, I believe this is prohibited by the American Boat Council, runs of rubber pipe are supposted to be 2' or less, so I am told. Secondly, the problem with long runs of rubber hose is that it tends to "Breathe" in and out with exhaust pulses, setting up a weird rpm-related vibration at certain engine speeds that will drive you nuts trying to track down. As far as inserting baffles in your existing fiberglass pipe, see my feeling above about fiberglass exhausts. Don't throw good efforts after bad. Rgds, Leprechaun
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Lep, Thanks for the reply, I guess the first question was a little silly. My question is if you lose a riser won't the engine overheat and therefore be shut down before any exhaust pipe melting occurs? Also, what does the cross section of a marine muffler look like, is it just a series of half circle dampers, like your copper one? Also, does just straight copper silence the exhaust at all? The run from the risers to the transom thru hulls is alot longer then 4', so what else did you use for exhaust pipe besides the four foot copper pieces?
Regards
Randy
Date: 06:40 p.m. on 03-09-2001
MarkG
normal member in standard member. 6. Re:Re:Re:Mufflers on 26' Shamrock
Randy,
No problem with running exhaust hose the full length of the bilge just so it is the wire reinforced hose and is secured every 2' with a clamp. I replaced the 3" galvanized pipe that Shamrock ran in earlier boats (because of cost) with 4" exhaust hose in my 22 Predator and saw nothing but better fuel economy (less back pressure). As far as the mufflers, I have fiberglass baffled ones near the outlet. If you are worried about melting them and sinking, put a ball valve downstream of them.
Date: 07:04 p.m. on 03-09-2001
Irish Wake
7. Re:Re:Re:Re:Mufflers on 26' Shamrock
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MarkG (03-09-2001 07:04 p.m.):
Randy,
No problem with running exhaust hose the full length of the bilge just so it is the wire reinforced hose and is secured every 2' with a clamp. I replaced the 3" galvanized pipe that Shamrock ran in earlier boats (because of cost) with 4" exhaust hose in my 22 Predator and saw nothing but better fuel economy (less back pressure). As far as the mufflers, I have fiberglass baffled ones near the outlet. If you are worried about melting them and sinking, put a ball valve downstream of them.
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Mark, Thanks for the reply, when you went from 3" to 4" did you change the thru hull transom exhaust flanges? What brand of mufflers do you have installed? How did you attach 4" exhaust hose to your 3" risers outlets/
Regards
Randy
Date: 07:26 p.m. on 03-09-2001
MarkG
normal member in standard member. 8. Re:Re:Re:Re:Re:Mufflers on 26' Shamrock
Randy,
Sorry, I should have elaborated a little. I had replaced my Indmar with a Mercruiser that had 4" risers. The mechanic had used a reducer to get down to existing 3" hose which then tied into the 8' long piece of 3" galv pipe and then into the baffled bronze thru hull fittings. My new mechanic suggested getting rid of the reducer, pipe, and baffled thru hulls to eliminate back pressure. I ran 4" hose all the way back to new 4" unbaffled thru hull fittings and installed Dapars silencers (found in West Marine catalog) and flapper valves on the outlet of the thru hulls. Without the mufflers, the new system was a lot louder than before but also a lot more efficient (better mpg using Floscan and vacuum guage) The Dapar mufflers quieted it down quite a bit w/o any noticeable drop in efficiency.
Date: 07:51 p.m. on 03-09-2001
Leprechaun
premium member in standard member. 9. Re:Mufflers on 26' Shamrock
last updated (1) date: 13:36 on 12-19-2001
Randy - sometimes you just cannot pay attention to everthing going on around you, or are just too dog tired and therefore not sharp and this is when problems occur. My buddy lost a riser 9 miles off and didn't see anything on his gauges and in fact wasn't aware anything was amiss until he smelled hot rubber. Turned around and there was a nice white cloud coming out of his port exhaust. The riser closed, but because he had a copper exhaust he was able to reduce speed to an idle and come home at 5 knots. The hose was charred, but it held. The copper pipe saved him from an ugly incident. Enough proof for me. Usually when you lose a riser it isn't 100% closed, maybe 95 - 98% and a tiny stream of water is still present, insufficient to properly cool the exhaust, but enough to keep the hose from puncturing if you cut back in time and just creep home. Usually, but not always. So why chance it with materials that tell you right on their labels that they are rated to 250 degrees? No thanks, I say do it once and do it right. As best as possible.
The straight copper pipes in my rig do seem quieter than the dopey rubber mufflers my Uncle had in his 20' Shammie. I don't think those mufflers were worth a damn and the previous owner spent good bucks having them installed. Don't forget that I have a swim platform and the fact that the pipes exhaust under the platform helps control the sound, I guess.
As far as using fiberglass piping or straight hose from riser to stern. To each his own. Neither option is for me, as I stated earlier. Regards, Leprechaun
Date: 09:16 p.m. on 03-09-2001
Irish Wake
10. Re:Re:Mufflers on 26' Shamrock
[quote]Leprechaun (03-09-2001 09:16 p.m.):
Lep, Thanks for the reply, I agree with everything you have said. I can only get the Sch. M cooper pipe in 20' sticks. How long is the run from the riser outlet to the transom thru hulls? Did you run 3" or 4"? Do you put the first baffle(closest to the riser) on the top or bottom? What do oyu use to close up the slit you cut, a welder or a torch? On my old engine, I always saw steam coming out of the thru hulls, even in the summer, do you think that wa a sign of restricted water flow?
Regards
Randy
Date: 09:14 a.m. on 03-10-2001
Leprechaun
premium member in standard member. 11. Re:Re:Re:Mufflers on 26' Shamrock
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Irish Wake (03-10-2001 09:14 a.m.):
[quote]Leprechaun (03-09-2001 09:16 p.m.):
Lep, Thanks for the reply, I agree with everything you have said. I can only get the Sch. M cooper pipe in 20' sticks. How long is the run from the riser outlet to the transom thru hulls? Did you run 3" or 4"? Do you put the first baffle(closest to the riser) on the top or bottom? What do oyu use to close up the slit you cut, a welder or a torch? On my old engine, I always saw steam coming out of the thru hulls, even in the summer, do you think that wa a sign of restricted water flow?
Regards
Randy
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Randy - man you are the original "Inquiring Mind" you just want to know! Lets see if I can help -
1/ - Schdule M pipe - 20' is gonna be expensive, now that I think of it, maybe the length I boayght 5 years ago was more than 8'. Wasn't 20' though.
2/ - I'm going down to the boat in a few minutes so I'll rip up the deck and measure the copper pipe lenghts I used. Your boat will be identical.
3/ My boat uses 3" exhausts.
4/ I don't think it matters if the forward baffle is up or down. Never thought much about that. But as I said, my boat is "Baffless" I used a straight run of unbaffled pipe.
5/ Slit closing - When you make the half-moons, leave a little material on the half-round side to kinda fold over the outside of the slit - and then you braise everthing together, and close up the slot with copper braising rod.
6/ Steam coming out of the exhaust is normal. Some steam that is. The quickie test for riser closure is as follows - run the boat hard, then when you get back to the dock leave the engine running and place both your hands atop the risers. Can you comfortably leave your hands there? If not, there's at least a partial clog. Don't be surprised if one side is significantly cooler than the other. Really quite normal and has to do with both the flow of cooling water as well as the RELATIVE flow in the risers. If you can't leave your hand on the risers, immediate remedial action is called for.
How'd I do?
Rgds, Leprechaun
Date: 11:24 a.m. on 03-10-2001
Leprechaun
premium member in standard member. 12. Re:Mufflers on 26' Shamrock
Re:Mufflers on 26' Shamrock
Message Randy - Here are the dimensions.
First - 39" of 3" exhaust hose coming off the riser.
Second - 48" copper pipe - 3" diameter.
Third - 29" of Exhaust Hose from the rear of the pipe to the thru-transom exhaust port.
Bear in mind that the exhaust hose measurements include the portion that's on the riser flange, overlapping the ends of the coppper pipe, and up over the flange of the thru-transoms. Don't forget that everything needs double SS hose clamps. That's a total of 8 clamps per side.
Oh yea, I almost forgot - I have these funky hard rubber silencer thingies on the outside of the thru-transoms, I think they might help cut the sharp exhaust rap a bit but I believe they aren't really necessary.
Hope I helped. Rgds, Leprechaun
Date: 04:49 p.m. on 03-10-2001
Irish Wake
13. Re:Re:Mufflers on 26' Shamrock
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Leprechaun (03-10-2001 04:49 p.m.):
Re:Mufflers on 26' Shamrock
Message Randy - Here are the dimensions.
First - 39" of 3" exhaust hose coming off the riser.
Second - 48" copper pipe - 3" diameter.
Third - 29" of Exhaust Hose from the rear of the pipe to the thru-transom exhaust port.
Bear in mind that the exhaust hose measurements include the portion that's on the riser flange, overlapping the ends of the coppper pipe, and up over the flange of the thru-transoms. Don't forget that everything needs double SS hose clamps. That's a total of 8 clamps per side.
Oh yea, I almost forgot - I have these funky hard rubber silencer thingies on the outside of the thru-transoms, I think they might help cut the sharp exhaust rap a bit but I believe they aren't really necessary.
Hope I helped. Rgds, Leprechaun
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Lep, Now that's information, thanks. One question, I promise, tell me more about those hard rubber things on the transom, those are what I'm looking for. Do they replace the flappers? Who make them and where might I find them. Also, I put 45 degree exhaust elbows in place of the flappers on my boat and I'm wondering if they caused water to be ingested into my engine, what do you think and how do you keep that from happening. Okay, maybe more then one but I tried.
Regards
Randy
P.S. Lep, I don't think I ever told you but I grew up in Shelter Island, my parents are from Malverne and Rockville Center and my wife is from Wauntau. Small world huh
Date: 10:56 a.m. on 03-11-2001
Leprechaun
premium member in standard member. 14. Re:Mufflers on 26' Shamrock
Randy - I honestly have no idea where the previous owner bought the exhaust thingies on my boat, I've never seen them in any catalog. I think a simple pair of rubber flappers would be fine. As far as how SW got in your engine, either your risers/manifolds were bad or you backed up hard and the water ran up your exhaust, not too many ways of it getting in there.
Malverne and Rockville Center are a little west of me, and I actually live in Wantagh, so you are right its a small world. Ask your wife what street in Wantagh she grew up on, I'm 1 block north of Merrick Rd. about 5 blocks from the water (actually Seaford) and hence my boat. Rgds, Leprechaun
Date: 11:18 a.m. on 03-11-2001
Irish Wake
15. Re:Re:Mufflers on 26' Shamrock
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Leprechaun (03-11-2001 11:18 a.m.):
Randy - I honestly have no idea where the previous owner bought the exhaust thingies on my boat, I've never seen them in any catalog. I think a simple pair of rubber flappers would be fine. As far as how SW got in your engine, either your risers/manifolds were bad or you backed up hard and the water ran up your exhaust, not too many ways of it getting in there.
Malverne and Rockville Center are a little west of me, and I actually live in Wantagh, so you are right its a small world. Ask your wife what street in Wantagh she grew up on, I'm 1 block north of Merrick Rd. about 5 blocks from the water (actually Seaford) and hence my boat. Rgds, Leprechaun
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Lep, My lovely wife grew up at 11 Wishbone Lane in Levittown. Could you comment on the grounding system you said you have installed on your boat. I don't think I have anything like that installed and want to install it while the engine is out.
Regards
Randy
Date: 11:35 a.m. on 03-11-2001
Leprechaun
premium member in standard member. 16. Re:Re:Re:Mufflers on 26' Shamrock
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Irish Wake (03-11-2001 11:35 a.m.):
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Leprechaun (03-11-2001 11:18 a.m.):
Randy - I honestly have no idea where the previous owner bought the exhaust thingies on my boat, I've never seen them in any catalog. I think a simple pair of rubber flappers would be fine. As far as how SW got in your engine, either your risers/manifolds were bad or you backed up hard and the water ran up your exhaust, not too many ways of it getting in there.
Malverne and Rockville Center are a little west of me, and I actually live in Wantagh, so you are right its a small world. Ask your wife what street in Wantagh she grew up on, I'm 1 block north of Merrick Rd. about 5 blocks from the water (actually Seaford) and hence my boat. Rgds, Leprechaun
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Lep, My lovely wife grew up at 11 Wishbone Lane in Levittown. Could you comment on the grounding system you said you have installed on your boat. I don't think I have anything like that installed and want to install it while the engine is out.
Regards
Randy
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Yep - Wishbone Lane you say? Ask your wife if she graduated from the Levittown or Island Trees School district. While my post office was Levittown growing up, I actually attended the Island Trees Schools. This might be even more of a co-inkidink than we first thought.
Anyways - all, and I mean ALL of the metal parts of my boat are tied to a dynaplate hull ground plate. That includes the engine/trans, exhaust, radar arch, rudder post and propshaft. Plus all the electronics use that circuit as their earth ground. By the way, if you do decide to do this the convention for the proper wire color is light green. Get yourself a contractors spool of insulated wire #6 gauge at Home Depot. Not internally tinned, but not necessary for this application.
Let me know about your wife's high school. Rgds, Leprechaun
Date: 10:15 p.m. on 03-11-2001
normal member in standard member. 1. Mufflers on 26' Shamrock
Does anyone have mufflers installed on their 26' Shamrock? If so, what brand, type and how are they mounted. The bilge is very tight and I can't see how it can be done.
Regards
Randy
Date: 05:00 p.m. on 03-08-2001
Leprechaun
premium member in standard member. 2. Re:Mufflers on 26' Shamrock
Randy - I just spent 30 minutes on another site trying to locate a response to this question I wrote last year, couldn't find it, so I'll try to keep it brief here. Right.
O.k. - so here's my take on this muffler question. IMHO no small inboard boat should ever have a pair of those hard-rubber nitrile or worse, fiberglas mufflers below the deck. If you are going to put a set on her, you need metal. Let me 'splain why. Many people are unaware that the exhaust hose in their boats is actually rated to withstand higher heat levels than the rubber or glass mufflers they are connected too. Don't believe me? Check into it. So what does this mean? It means that in the unfortunate event of losing a riser to clogging offshore, the hose will last far longer than the muffler, the muffler will melt, hole and sink the boat. No bull. Proven fact. As you are probably aware, the exhaust system of a Shamrock is actually below the waterline. Always full of water. So a hole ANYWHERE south of the risers will cause some tense moments, if not total panic. No bilge pumps we could employ in these boats could possibly keep up with the flow a hole the size of a silver dollar would produce. Glug, glug, down she goes. A good friend actually witnessed a 35' Lobsterboat off Mountauk, L.I. lose a riser, hole his rubber muffler and if it weren't for a couple of gas-powered pumps that the Coasties heli-lifted to the boat, she was a gonner for sure. Makes you kinda re-think the whole "My boat is too loud for my wife" thing.
So what's a guy to do? Allow me to introduce you to "Freddie's Famous Copper Shamrock Exhaust." And this is how you make it yourself. I will use my Predator 26 as an example as I was there during fabrication/installation. First - go to your local plumbing supply store and order an 8' length of "Schedule M" Copper pipe in the correct diameter. In my case that was 3", but in a 20' or 22' Shammie it could very well be 2 or 2.5" exhaust hose and hence, pipe. DO NOT allow the supply house to sell you that cheap-ass thin regular plumbing pipe. It will work for a while, but who knows? Get M grade. They might have to special order it, it took 2 days to get mine. Now cut that 8' length in half. This will give you, obviously 2 4' sections which will be your mufflers. Now on my rig, we installed no baffling, so its a little bit louder than the other boats Freddie's done, but with my exhaust exiting under my swim platform the sound is thrown down away from the cockpit and we can actually conduct normal conversation at the helm while underway.
If you want to install sound-cancelling baffles what you need to do is get more copper - here the cheap thin stuff will work. Cut off a piece of the other pipe around 6" long and then cut that piece again inorder to get a flat piece after banging it flat. Now what you are gonna do is make inserts, which will resemble a half-moon that we will be installing in the muffler pipe. They need to be round on one side and straight across on the other and be exactly 1.5" diameter. They will obviously inhibit flow in exactly 50% of the inside of the pipe. Take the original pipe and exactly 1 foot from the end, make a slot cut 1/2 way thru and take the baffle and braise it into the slot using copper rod for the braising material. Now go to the other end of the pipe and 180-degrees OPPOSITE to first baffle location, cut a second slot 12" in and braise in the second baffle. That's really it. Not complicated, but damned effective and impervious to deterioration or worse to failure due to heat. Now if you want to get fancy (Like I did) you can braise two bronze bolts to each of the pipes and tie them into your hull ground/bonding system. As far as securing them to the boat - I ran them down both longitudinal bulkheads, on either side of the cockpit belly box, and used a few strips of copper as straps to secure them. Try not to use real long screws here, the fuel tanks are real close to the other side of the bulkheads.
I told you I would keep it brief, didn't I? Rgds, Leprechaun
Date: 08:59 p.m. on 03-08-2001
Irish Wake
3. Re:Re:Mufflers on 26' Shamrock
Lep, A couple of followups, does copper have a higher heat rating then fiberglass? I have fiberglass exhaust from the exhaust elbow back to the thru hulls. Does the half moon baffles restrict the flow of water through the exhuast and therefore does it cause excessive back pressure? Also, would rubber exhuast hose all the way from the riser elbows to the thru hulls quiet things down? Why can't I just put those half moon baffles in the fiberglass exhaust pipes that are already installed? Let me know what you think
Regards
Randy
Date: 12:32 p.m. on 03-09-2001
Leprechaun
premium member in standard member. 4. Re:Mufflers on 26' Shamrock
Randy - I don't really understand your first question. Are you asking if Copper pipe can resist heat better than fiberglas? If that's the question, then yes, of course, is the answer. Regarding having fiberglass tubes from the exhaust riser to the transom, I would change that immediately, see my reasons above. The half-moon baffles have no effect we can observe on the engine's performance, same part-throttle response and gph fuel burn and exactly the same top end speed and rpms, just 1/2 the noise.
As far as using rubber exhaust hose all the way from the risers to the transom, two problems there. First, I believe this is prohibited by the American Boat Council, runs of rubber pipe are supposted to be 2' or less, so I am told. Secondly, the problem with long runs of rubber hose is that it tends to "Breathe" in and out with exhaust pulses, setting up a weird rpm-related vibration at certain engine speeds that will drive you nuts trying to track down. As far as inserting baffles in your existing fiberglass pipe, see my feeling above about fiberglass exhausts. Don't throw good efforts after bad. Rgds, Leprechaun
Date: 06:04 p.m. on 03-09-2001
Irish Wake
5. Re:Re:Mufflers on 26' Shamrock
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Leprechaun (03-09-2001 06:04 p.m.):
Randy - I don't really understand your first question. Are you asking if Copper pipe can resist heat better than fiberglas? If that's the question, then yes, of course, is the answer. Regarding having fiberglass tubes from the exhaust riser to the transom, I would change that immediately, see my reasons above. The half-moon baffles have no effect we can observe on the engine's performance, same part-throttle response and gph fuel burn and exactly the same top end speed and rpms, just 1/2 the noise.
As far as using rubber exhaust hose all the way from the risers to the transom, two problems there. First, I believe this is prohibited by the American Boat Council, runs of rubber pipe are supposted to be 2' or less, so I am told. Secondly, the problem with long runs of rubber hose is that it tends to "Breathe" in and out with exhaust pulses, setting up a weird rpm-related vibration at certain engine speeds that will drive you nuts trying to track down. As far as inserting baffles in your existing fiberglass pipe, see my feeling above about fiberglass exhausts. Don't throw good efforts after bad. Rgds, Leprechaun
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Lep, Thanks for the reply, I guess the first question was a little silly. My question is if you lose a riser won't the engine overheat and therefore be shut down before any exhaust pipe melting occurs? Also, what does the cross section of a marine muffler look like, is it just a series of half circle dampers, like your copper one? Also, does just straight copper silence the exhaust at all? The run from the risers to the transom thru hulls is alot longer then 4', so what else did you use for exhaust pipe besides the four foot copper pieces?
Regards
Randy
Date: 06:40 p.m. on 03-09-2001
MarkG
normal member in standard member. 6. Re:Re:Re:Mufflers on 26' Shamrock
Randy,
No problem with running exhaust hose the full length of the bilge just so it is the wire reinforced hose and is secured every 2' with a clamp. I replaced the 3" galvanized pipe that Shamrock ran in earlier boats (because of cost) with 4" exhaust hose in my 22 Predator and saw nothing but better fuel economy (less back pressure). As far as the mufflers, I have fiberglass baffled ones near the outlet. If you are worried about melting them and sinking, put a ball valve downstream of them.
Date: 07:04 p.m. on 03-09-2001
Irish Wake
7. Re:Re:Re:Re:Mufflers on 26' Shamrock
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MarkG (03-09-2001 07:04 p.m.):
Randy,
No problem with running exhaust hose the full length of the bilge just so it is the wire reinforced hose and is secured every 2' with a clamp. I replaced the 3" galvanized pipe that Shamrock ran in earlier boats (because of cost) with 4" exhaust hose in my 22 Predator and saw nothing but better fuel economy (less back pressure). As far as the mufflers, I have fiberglass baffled ones near the outlet. If you are worried about melting them and sinking, put a ball valve downstream of them.
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Mark, Thanks for the reply, when you went from 3" to 4" did you change the thru hull transom exhaust flanges? What brand of mufflers do you have installed? How did you attach 4" exhaust hose to your 3" risers outlets/
Regards
Randy
Date: 07:26 p.m. on 03-09-2001
MarkG
normal member in standard member. 8. Re:Re:Re:Re:Re:Mufflers on 26' Shamrock
Randy,
Sorry, I should have elaborated a little. I had replaced my Indmar with a Mercruiser that had 4" risers. The mechanic had used a reducer to get down to existing 3" hose which then tied into the 8' long piece of 3" galv pipe and then into the baffled bronze thru hull fittings. My new mechanic suggested getting rid of the reducer, pipe, and baffled thru hulls to eliminate back pressure. I ran 4" hose all the way back to new 4" unbaffled thru hull fittings and installed Dapars silencers (found in West Marine catalog) and flapper valves on the outlet of the thru hulls. Without the mufflers, the new system was a lot louder than before but also a lot more efficient (better mpg using Floscan and vacuum guage) The Dapar mufflers quieted it down quite a bit w/o any noticeable drop in efficiency.
Date: 07:51 p.m. on 03-09-2001
Leprechaun
premium member in standard member. 9. Re:Mufflers on 26' Shamrock
last updated (1) date: 13:36 on 12-19-2001
Randy - sometimes you just cannot pay attention to everthing going on around you, or are just too dog tired and therefore not sharp and this is when problems occur. My buddy lost a riser 9 miles off and didn't see anything on his gauges and in fact wasn't aware anything was amiss until he smelled hot rubber. Turned around and there was a nice white cloud coming out of his port exhaust. The riser closed, but because he had a copper exhaust he was able to reduce speed to an idle and come home at 5 knots. The hose was charred, but it held. The copper pipe saved him from an ugly incident. Enough proof for me. Usually when you lose a riser it isn't 100% closed, maybe 95 - 98% and a tiny stream of water is still present, insufficient to properly cool the exhaust, but enough to keep the hose from puncturing if you cut back in time and just creep home. Usually, but not always. So why chance it with materials that tell you right on their labels that they are rated to 250 degrees? No thanks, I say do it once and do it right. As best as possible.
The straight copper pipes in my rig do seem quieter than the dopey rubber mufflers my Uncle had in his 20' Shammie. I don't think those mufflers were worth a damn and the previous owner spent good bucks having them installed. Don't forget that I have a swim platform and the fact that the pipes exhaust under the platform helps control the sound, I guess.
As far as using fiberglass piping or straight hose from riser to stern. To each his own. Neither option is for me, as I stated earlier. Regards, Leprechaun
Date: 09:16 p.m. on 03-09-2001
Irish Wake
10. Re:Re:Mufflers on 26' Shamrock
[quote]Leprechaun (03-09-2001 09:16 p.m.):
Lep, Thanks for the reply, I agree with everything you have said. I can only get the Sch. M cooper pipe in 20' sticks. How long is the run from the riser outlet to the transom thru hulls? Did you run 3" or 4"? Do you put the first baffle(closest to the riser) on the top or bottom? What do oyu use to close up the slit you cut, a welder or a torch? On my old engine, I always saw steam coming out of the thru hulls, even in the summer, do you think that wa a sign of restricted water flow?
Regards
Randy
Date: 09:14 a.m. on 03-10-2001
Leprechaun
premium member in standard member. 11. Re:Re:Re:Mufflers on 26' Shamrock
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Irish Wake (03-10-2001 09:14 a.m.):
[quote]Leprechaun (03-09-2001 09:16 p.m.):
Lep, Thanks for the reply, I agree with everything you have said. I can only get the Sch. M cooper pipe in 20' sticks. How long is the run from the riser outlet to the transom thru hulls? Did you run 3" or 4"? Do you put the first baffle(closest to the riser) on the top or bottom? What do oyu use to close up the slit you cut, a welder or a torch? On my old engine, I always saw steam coming out of the thru hulls, even in the summer, do you think that wa a sign of restricted water flow?
Regards
Randy
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Randy - man you are the original "Inquiring Mind" you just want to know! Lets see if I can help -
1/ - Schdule M pipe - 20' is gonna be expensive, now that I think of it, maybe the length I boayght 5 years ago was more than 8'. Wasn't 20' though.
2/ - I'm going down to the boat in a few minutes so I'll rip up the deck and measure the copper pipe lenghts I used. Your boat will be identical.
3/ My boat uses 3" exhausts.
4/ I don't think it matters if the forward baffle is up or down. Never thought much about that. But as I said, my boat is "Baffless" I used a straight run of unbaffled pipe.
5/ Slit closing - When you make the half-moons, leave a little material on the half-round side to kinda fold over the outside of the slit - and then you braise everthing together, and close up the slot with copper braising rod.
6/ Steam coming out of the exhaust is normal. Some steam that is. The quickie test for riser closure is as follows - run the boat hard, then when you get back to the dock leave the engine running and place both your hands atop the risers. Can you comfortably leave your hands there? If not, there's at least a partial clog. Don't be surprised if one side is significantly cooler than the other. Really quite normal and has to do with both the flow of cooling water as well as the RELATIVE flow in the risers. If you can't leave your hand on the risers, immediate remedial action is called for.
How'd I do?
Rgds, Leprechaun
Date: 11:24 a.m. on 03-10-2001
Leprechaun
premium member in standard member. 12. Re:Mufflers on 26' Shamrock
Re:Mufflers on 26' Shamrock
Message Randy - Here are the dimensions.
First - 39" of 3" exhaust hose coming off the riser.
Second - 48" copper pipe - 3" diameter.
Third - 29" of Exhaust Hose from the rear of the pipe to the thru-transom exhaust port.
Bear in mind that the exhaust hose measurements include the portion that's on the riser flange, overlapping the ends of the coppper pipe, and up over the flange of the thru-transoms. Don't forget that everything needs double SS hose clamps. That's a total of 8 clamps per side.
Oh yea, I almost forgot - I have these funky hard rubber silencer thingies on the outside of the thru-transoms, I think they might help cut the sharp exhaust rap a bit but I believe they aren't really necessary.
Hope I helped. Rgds, Leprechaun
Date: 04:49 p.m. on 03-10-2001
Irish Wake
13. Re:Re:Mufflers on 26' Shamrock
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Leprechaun (03-10-2001 04:49 p.m.):
Re:Mufflers on 26' Shamrock
Message Randy - Here are the dimensions.
First - 39" of 3" exhaust hose coming off the riser.
Second - 48" copper pipe - 3" diameter.
Third - 29" of Exhaust Hose from the rear of the pipe to the thru-transom exhaust port.
Bear in mind that the exhaust hose measurements include the portion that's on the riser flange, overlapping the ends of the coppper pipe, and up over the flange of the thru-transoms. Don't forget that everything needs double SS hose clamps. That's a total of 8 clamps per side.
Oh yea, I almost forgot - I have these funky hard rubber silencer thingies on the outside of the thru-transoms, I think they might help cut the sharp exhaust rap a bit but I believe they aren't really necessary.
Hope I helped. Rgds, Leprechaun
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Lep, Now that's information, thanks. One question, I promise, tell me more about those hard rubber things on the transom, those are what I'm looking for. Do they replace the flappers? Who make them and where might I find them. Also, I put 45 degree exhaust elbows in place of the flappers on my boat and I'm wondering if they caused water to be ingested into my engine, what do you think and how do you keep that from happening. Okay, maybe more then one but I tried.
Regards
Randy
P.S. Lep, I don't think I ever told you but I grew up in Shelter Island, my parents are from Malverne and Rockville Center and my wife is from Wauntau. Small world huh
Date: 10:56 a.m. on 03-11-2001
Leprechaun
premium member in standard member. 14. Re:Mufflers on 26' Shamrock
Randy - I honestly have no idea where the previous owner bought the exhaust thingies on my boat, I've never seen them in any catalog. I think a simple pair of rubber flappers would be fine. As far as how SW got in your engine, either your risers/manifolds were bad or you backed up hard and the water ran up your exhaust, not too many ways of it getting in there.
Malverne and Rockville Center are a little west of me, and I actually live in Wantagh, so you are right its a small world. Ask your wife what street in Wantagh she grew up on, I'm 1 block north of Merrick Rd. about 5 blocks from the water (actually Seaford) and hence my boat. Rgds, Leprechaun
Date: 11:18 a.m. on 03-11-2001
Irish Wake
15. Re:Re:Mufflers on 26' Shamrock
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Leprechaun (03-11-2001 11:18 a.m.):
Randy - I honestly have no idea where the previous owner bought the exhaust thingies on my boat, I've never seen them in any catalog. I think a simple pair of rubber flappers would be fine. As far as how SW got in your engine, either your risers/manifolds were bad or you backed up hard and the water ran up your exhaust, not too many ways of it getting in there.
Malverne and Rockville Center are a little west of me, and I actually live in Wantagh, so you are right its a small world. Ask your wife what street in Wantagh she grew up on, I'm 1 block north of Merrick Rd. about 5 blocks from the water (actually Seaford) and hence my boat. Rgds, Leprechaun
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Lep, My lovely wife grew up at 11 Wishbone Lane in Levittown. Could you comment on the grounding system you said you have installed on your boat. I don't think I have anything like that installed and want to install it while the engine is out.
Regards
Randy
Date: 11:35 a.m. on 03-11-2001
Leprechaun
premium member in standard member. 16. Re:Re:Re:Mufflers on 26' Shamrock
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Irish Wake (03-11-2001 11:35 a.m.):
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Leprechaun (03-11-2001 11:18 a.m.):
Randy - I honestly have no idea where the previous owner bought the exhaust thingies on my boat, I've never seen them in any catalog. I think a simple pair of rubber flappers would be fine. As far as how SW got in your engine, either your risers/manifolds were bad or you backed up hard and the water ran up your exhaust, not too many ways of it getting in there.
Malverne and Rockville Center are a little west of me, and I actually live in Wantagh, so you are right its a small world. Ask your wife what street in Wantagh she grew up on, I'm 1 block north of Merrick Rd. about 5 blocks from the water (actually Seaford) and hence my boat. Rgds, Leprechaun
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Lep, My lovely wife grew up at 11 Wishbone Lane in Levittown. Could you comment on the grounding system you said you have installed on your boat. I don't think I have anything like that installed and want to install it while the engine is out.
Regards
Randy
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Yep - Wishbone Lane you say? Ask your wife if she graduated from the Levittown or Island Trees School district. While my post office was Levittown growing up, I actually attended the Island Trees Schools. This might be even more of a co-inkidink than we first thought.
Anyways - all, and I mean ALL of the metal parts of my boat are tied to a dynaplate hull ground plate. That includes the engine/trans, exhaust, radar arch, rudder post and propshaft. Plus all the electronics use that circuit as their earth ground. By the way, if you do decide to do this the convention for the proper wire color is light green. Get yourself a contractors spool of insulated wire #6 gauge at Home Depot. Not internally tinned, but not necessary for this application.
Let me know about your wife's high school. Rgds, Leprechaun
Date: 10:15 p.m. on 03-11-2001