Repairing Hunter 40 damage from Hurricane Matthew
- Thread starter B757Captain
- Start date
Greetings all:
I just returned to Japan after a quick trip back to the states. Got a little bit done on the boat but not as much as I would have liked. Some life stuff interfered as follows:
I had worked out a leave period while training is ongoing here in Japan and headed back to the US for a couple of weeks. Literally the morning after I arrived home I get the phone call - my uncle passed away. So it's time to plan for going to the funeral. Problem is, that hadn't been arranged yet! So to stay as flexible as possible I planned on borrowing my buddy's plane for the trip (SC to New Mexico). All this while I am battling severe jet-lag. Long story short I was thwarted by the weather enroute - weird for me since normally I fly over the weather, not under it! I had to cancel the trip at the last minute but there went essentially the first week I was home.
Then to top things off we (the local island community here) got word that the current owners of the marina had found a buyer and it will be sold. What's left of it anyhow. There's lots of weird secret politics going on between the marina owners, the island, etc., way above my pay grade, but the long and short of it is the status of the marina remaining a marina is not certain. There's a 99% chance that the marina will remain but I can't take the chance on that 1%.
So with a week remaining to do some work I had to focus on what would happen if the new owners decide to turn the marina/boatyard into a resort or gaggle of condos! That means getting the boat able to float!
Stay tuned!
Mark
I just returned to Japan after a quick trip back to the states. Got a little bit done on the boat but not as much as I would have liked. Some life stuff interfered as follows:
I had worked out a leave period while training is ongoing here in Japan and headed back to the US for a couple of weeks. Literally the morning after I arrived home I get the phone call - my uncle passed away. So it's time to plan for going to the funeral. Problem is, that hadn't been arranged yet! So to stay as flexible as possible I planned on borrowing my buddy's plane for the trip (SC to New Mexico). All this while I am battling severe jet-lag. Long story short I was thwarted by the weather enroute - weird for me since normally I fly over the weather, not under it! I had to cancel the trip at the last minute but there went essentially the first week I was home.
Then to top things off we (the local island community here) got word that the current owners of the marina had found a buyer and it will be sold. What's left of it anyhow. There's lots of weird secret politics going on between the marina owners, the island, etc., way above my pay grade, but the long and short of it is the status of the marina remaining a marina is not certain. There's a 99% chance that the marina will remain but I can't take the chance on that 1%.
So with a week remaining to do some work I had to focus on what would happen if the new owners decide to turn the marina/boatyard into a resort or gaggle of condos! That means getting the boat able to float!
Stay tuned!
Mark
Update: Making sure water stays on the outside!
My original plan for this trip home was to install some portlights in the hull sides for aft cabin ventilation. With everything else going on, that didn't happen! I had to instead plan for worst-case potential that the boat might need to be moved while I am 8000 miles away! All of us boat owners in the marina have been strategizing and we came up with lots of ideas but we are still lacking the one necessary piece of information: What will happen with the marina?
We figure that there is a better than average chance that things at the marina will remain status quo. But there is a chance that the new owners really want the property for something other than a marina. That causes some (obvious) problems for those of us still here. As a short update on the current status of the marina, it's a boatyard, dry stack and boathouse. No wet slips and the current owners have no intention of rebuilding. There are about 50 total boats here of which 25 or so are not trailerable, thus need homes either in the water or in a yard with a lift. The problem is all the marinas in the area are full with waiting lists (due to our marina no longer existing!) and no other dry storage facilities close by. So if the new owners decide to close the marina and yard there's no place to go close by - and we are hoping that they realize that and give us some time to sort things out. However there is always the possibility that they will walk in one day and tell us we have a week to leave because the bulldozers are on the way! Granted not likely but possible.
So I spent my remaining time home getting the last hole in the boat sealed up so if necessary it can be splashed and towed to another yard. No pics unfortunately but here's a summary:
Before I left I had temporarily installed the shaft and strut, mainly just to clean up the garage. So I mounted and sealed the strut to the hull and reinstalled the transmission. Next up was to re-seat the shaft into the trans coupler. From there I could eyeball the engine location. The goal being to get the transmission flange in a point in space where, when attached, the shaft would center in the shaft log (just gross location for now, not alignment). Since I had the engine and bearers out and replaced the mounts I had no idea where things would be and - huge surprise! - I nailed it vertically and was within 1/4" laterally! Pure luck! So a quick lift on the engine to slide it sideways and now its time for alignment. There's lots of videos on Youtube about how to align an engine so I won't go into the details, but the engine and shaft are aligned and bolted down. Next up was to finish up the PSS shaft seal and the boat is once again watertight.
Now if it needs to be moved it can be. Best case scenario is things stay as they are. Next best is if it needs to be moved we will have a grace period to make arrangements. In this case I will probably be able to do it on my next trip home. In that case I will be able to hook up a temporary exhaust system and raw water cooling and I'll be able to motor to wherever I can find a new home. Worst case is she has to be moved while I'm here in Japan. In this case it can be towed to her new home.
If I had a little more time I could have slapped some bottom paint on and found a wet slip and continued the repairs to the interior and dealt with the remaining hull repairs later - that might still be an option, though not one I'm thrilled about. I'll just have to see how things play out. For now,
Cheers from Narita,
Mark-san
My original plan for this trip home was to install some portlights in the hull sides for aft cabin ventilation. With everything else going on, that didn't happen! I had to instead plan for worst-case potential that the boat might need to be moved while I am 8000 miles away! All of us boat owners in the marina have been strategizing and we came up with lots of ideas but we are still lacking the one necessary piece of information: What will happen with the marina?
We figure that there is a better than average chance that things at the marina will remain status quo. But there is a chance that the new owners really want the property for something other than a marina. That causes some (obvious) problems for those of us still here. As a short update on the current status of the marina, it's a boatyard, dry stack and boathouse. No wet slips and the current owners have no intention of rebuilding. There are about 50 total boats here of which 25 or so are not trailerable, thus need homes either in the water or in a yard with a lift. The problem is all the marinas in the area are full with waiting lists (due to our marina no longer existing!) and no other dry storage facilities close by. So if the new owners decide to close the marina and yard there's no place to go close by - and we are hoping that they realize that and give us some time to sort things out. However there is always the possibility that they will walk in one day and tell us we have a week to leave because the bulldozers are on the way! Granted not likely but possible.
So I spent my remaining time home getting the last hole in the boat sealed up so if necessary it can be splashed and towed to another yard. No pics unfortunately but here's a summary:
Before I left I had temporarily installed the shaft and strut, mainly just to clean up the garage. So I mounted and sealed the strut to the hull and reinstalled the transmission. Next up was to re-seat the shaft into the trans coupler. From there I could eyeball the engine location. The goal being to get the transmission flange in a point in space where, when attached, the shaft would center in the shaft log (just gross location for now, not alignment). Since I had the engine and bearers out and replaced the mounts I had no idea where things would be and - huge surprise! - I nailed it vertically and was within 1/4" laterally! Pure luck! So a quick lift on the engine to slide it sideways and now its time for alignment. There's lots of videos on Youtube about how to align an engine so I won't go into the details, but the engine and shaft are aligned and bolted down. Next up was to finish up the PSS shaft seal and the boat is once again watertight.
Now if it needs to be moved it can be. Best case scenario is things stay as they are. Next best is if it needs to be moved we will have a grace period to make arrangements. In this case I will probably be able to do it on my next trip home. In that case I will be able to hook up a temporary exhaust system and raw water cooling and I'll be able to motor to wherever I can find a new home. Worst case is she has to be moved while I'm here in Japan. In this case it can be towed to her new home.
If I had a little more time I could have slapped some bottom paint on and found a wet slip and continued the repairs to the interior and dealt with the remaining hull repairs later - that might still be an option, though not one I'm thrilled about. I'll just have to see how things play out. For now,
Cheers from Narita,
Mark-san
Mark - thanks for the update - it is a real inspiration for the minor work I do on my boat.
-- Keep flying Boeing and fund my pension!!
Les
-- Keep flying Boeing and fund my pension!!
Les
Good evening fellas!
I'm back in the states for a few weeks on leave and boat repairs are happening! My plan is to work on items 45,46,48 and 50 on the list of 2000 or so things to get done.
I figured I would sort out the aux fuel tank, install the exhaust system and engine systems, plus work on repairing the damage to the bow, bow rollers and stem. Then if there is time I'll start fabricating the under-floor water tanks and continue interior paint.
First thing I did was yank out the old aux fuel tank:
This tank used to be the aft water tank but I converted it a few years ago for extra fuel. The problem with the tank is that it is made from really thin-wall aluminum, it's original to the boat and I really never had a whole lot of confidence in it. Now's the time to rectify that! The tank holds about 47 gallons and my options are to have a replacement fabricated or buy a pre-molded plastic tank. I decided on a plastic tank (40 gals). I'm giving up a little capacity but total fuel capacity of the main and new aux tank will be 75 gallons so I'm not giving up too much. There was a huge cost savings - that extra 7 gallons would have cost an extra $500!
I also removed rest of the original exhaust system, engine wiring and controls so I could clean up the aft cabin. The new exhaust will have to be installed so I can build the platform for the new fuel tank. Stay tuned - next up is the drama of redesigning the exhaust!
I'm also replacing all the images in previous pages - switching from photobucket to imgur before PB blocks my account. That will take a few days as I get to it.
Cheers,
Mark
I'm back in the states for a few weeks on leave and boat repairs are happening! My plan is to work on items 45,46,48 and 50 on the list of 2000 or so things to get done.
I figured I would sort out the aux fuel tank, install the exhaust system and engine systems, plus work on repairing the damage to the bow, bow rollers and stem. Then if there is time I'll start fabricating the under-floor water tanks and continue interior paint.
First thing I did was yank out the old aux fuel tank:
This tank used to be the aft water tank but I converted it a few years ago for extra fuel. The problem with the tank is that it is made from really thin-wall aluminum, it's original to the boat and I really never had a whole lot of confidence in it. Now's the time to rectify that! The tank holds about 47 gallons and my options are to have a replacement fabricated or buy a pre-molded plastic tank. I decided on a plastic tank (40 gals). I'm giving up a little capacity but total fuel capacity of the main and new aux tank will be 75 gallons so I'm not giving up too much. There was a huge cost savings - that extra 7 gallons would have cost an extra $500!
I also removed rest of the original exhaust system, engine wiring and controls so I could clean up the aft cabin. The new exhaust will have to be installed so I can build the platform for the new fuel tank. Stay tuned - next up is the drama of redesigning the exhaust!
I'm also replacing all the images in previous pages - switching from photobucket to imgur before PB blocks my account. That will take a few days as I get to it.
Cheers,
Mark
Area prep and odds & ends:
After getting the old exhaust and other engine systems removed or at least moved out of the way it was time to clean and prep for paint in the aft cabin. I also worked on a few items that I didn't have time to finish last time I was home. I removed the last of the bulkheads (I had finished the fitting but didn't have time to paint and clearcoat it. It is the biggest of the bulkheads and I had to make it in two pieces and assemble it in the boat.
On the sawhorses in the cabin, getting primer and paint:
It takes up most of the main cabin area!
I also figured it was a good time to finish moving the thru-hulls/seacocks for the aft head. I made a 3/4" thick glass backing plate for the seacocks, measured and test fit the locations and prepped the hull for the backing plate. I drilled the hole for the larger thru-hull so I could slip a c-clamp through the hole when it was time to glue it in:
I mixed in some cabosil with West Systems 6-10, lined everything up, glued and clamped in place:
While that was curing I worked on prepping the aft cabin for paint. I have to do this in sections - I can't reach far enough over wet paint to do it all in one go:
Two coats and a day or two to cure so I can walk on it and reach some more!
Next up - more paint and exhaust drama!
Cheers,
Mark-san
After getting the old exhaust and other engine systems removed or at least moved out of the way it was time to clean and prep for paint in the aft cabin. I also worked on a few items that I didn't have time to finish last time I was home. I removed the last of the bulkheads (I had finished the fitting but didn't have time to paint and clearcoat it. It is the biggest of the bulkheads and I had to make it in two pieces and assemble it in the boat.
On the sawhorses in the cabin, getting primer and paint:
It takes up most of the main cabin area!
I also figured it was a good time to finish moving the thru-hulls/seacocks for the aft head. I made a 3/4" thick glass backing plate for the seacocks, measured and test fit the locations and prepped the hull for the backing plate. I drilled the hole for the larger thru-hull so I could slip a c-clamp through the hole when it was time to glue it in:
I mixed in some cabosil with West Systems 6-10, lined everything up, glued and clamped in place:
While that was curing I worked on prepping the aft cabin for paint. I have to do this in sections - I can't reach far enough over wet paint to do it all in one go:
Two coats and a day or two to cure so I can walk on it and reach some more!
Next up - more paint and exhaust drama!
Cheers,
Mark-san
Re-thinking the exhaust system:
I had known for a while that the exhaust system needed some attention and the hurricane didn't improve this! I knew that the mixing elbow was probably close to replacement time and I had never checked the lift muffler. So with everything now out of the boat it was a good time to inspect what I had. I found a few things:
This was a section of the exhaust hose - of course it was in the most inaccessible location (for inspection purposes). The mixing elbow didn't look too good but there was still some daylight showing through it:
Still needs replacement though. The lift muffler actually looked pretty good and portions of the rest of the exhaust hose were ok, but still in need of some TLC. Now comes the question: just like other parts of the boat, can I make it better? The factory exhaust was a Rube-Goldberg-esque setup that was a huge compromise between Hunter, Yanmar and Mack-Boring. The basic problem was that the engine exhaust outlet sits about 1" or so below the waterline, the area below the engine is the lowest point of the boat, and the factory mixing elbow for the 4JHE exits the manifold and turns down at a 45 then introduces the water. Yanmar finally signed off on the system after Mack-Boring cobbled together a setup that incorporated the mixing elbow from the 3 cyl. Yanmar. They de-rated the engine hp in the process. Duh!
So to describe it, the exhaust leaves the manifold, turns 90 degrees up through a cast screw-in plumbing fitting to the double thread coupler to the mixing elbow. Then the exhaust hose is fitted and turns 90 degrees forward running over the heat exchanger then turns straight down in front of the engine to the lift muffler, located under the front of the engine. Then through the LM back to hose that runs under to the back of the engine then the hose turns 90 straight up 3 1/2 feet to a siphon loop. After the siphon loop the hose runs back down the back of the engine and under the aft bunk then turns 90 to starboard, makes a big half-loop through the aft bulkhead running over the aft water tank to end at the straight-down outlet at the base of the transom. Got all that? I measured the hoses - 29 feet after I eliminated about 7 feet of hose a few years ago by re-routing the rear loop! I'm sure there was just a little excess backpressure!
So, can I do better? Sure. But how? Using the correct mixing elbow introduces the same problem the factory originally had - there's not enough hose length from the engine to the lift muffler to contain all the residual water with the engine shut off. There's not enough space anywhere (except under the engine) to place a large enough lift muffler to contain all the water. So that's out.
Next idea - KISS! What's the simplest solution. Come straight up from the engine into a siphon loop, then down to a LM under the bunk, then straight run to the exit. Problem - the siphon loop needs to be almost 2' above the engine. That's a lot of metal to be supported by the weld at the manifold flange. Plus that's 2' of hot exhaust before I can introduce cooling water to the exhaust.
The solution: modern automotive design to the rescue! Here's a teaser:
Next up: the new design!
Cheers,
Mark-san
I had known for a while that the exhaust system needed some attention and the hurricane didn't improve this! I knew that the mixing elbow was probably close to replacement time and I had never checked the lift muffler. So with everything now out of the boat it was a good time to inspect what I had. I found a few things:
This was a section of the exhaust hose - of course it was in the most inaccessible location (for inspection purposes). The mixing elbow didn't look too good but there was still some daylight showing through it:
Still needs replacement though. The lift muffler actually looked pretty good and portions of the rest of the exhaust hose were ok, but still in need of some TLC. Now comes the question: just like other parts of the boat, can I make it better? The factory exhaust was a Rube-Goldberg-esque setup that was a huge compromise between Hunter, Yanmar and Mack-Boring. The basic problem was that the engine exhaust outlet sits about 1" or so below the waterline, the area below the engine is the lowest point of the boat, and the factory mixing elbow for the 4JHE exits the manifold and turns down at a 45 then introduces the water. Yanmar finally signed off on the system after Mack-Boring cobbled together a setup that incorporated the mixing elbow from the 3 cyl. Yanmar. They de-rated the engine hp in the process. Duh!
So to describe it, the exhaust leaves the manifold, turns 90 degrees up through a cast screw-in plumbing fitting to the double thread coupler to the mixing elbow. Then the exhaust hose is fitted and turns 90 degrees forward running over the heat exchanger then turns straight down in front of the engine to the lift muffler, located under the front of the engine. Then through the LM back to hose that runs under to the back of the engine then the hose turns 90 straight up 3 1/2 feet to a siphon loop. After the siphon loop the hose runs back down the back of the engine and under the aft bunk then turns 90 to starboard, makes a big half-loop through the aft bulkhead running over the aft water tank to end at the straight-down outlet at the base of the transom. Got all that? I measured the hoses - 29 feet after I eliminated about 7 feet of hose a few years ago by re-routing the rear loop! I'm sure there was just a little excess backpressure!
So, can I do better? Sure. But how? Using the correct mixing elbow introduces the same problem the factory originally had - there's not enough hose length from the engine to the lift muffler to contain all the residual water with the engine shut off. There's not enough space anywhere (except under the engine) to place a large enough lift muffler to contain all the water. So that's out.
Next idea - KISS! What's the simplest solution. Come straight up from the engine into a siphon loop, then down to a LM under the bunk, then straight run to the exit. Problem - the siphon loop needs to be almost 2' above the engine. That's a lot of metal to be supported by the weld at the manifold flange. Plus that's 2' of hot exhaust before I can introduce cooling water to the exhaust.
The solution: modern automotive design to the rescue! Here's a teaser:
Next up: the new design!
Cheers,
Mark-san
While I was sorting through the re-engineering required for the exhaust, I continued on with some of the other projects.
With the thru-hull backing plate dry, a little paint to make it look nice:
Here checking that the depth of the thru-hulls are ok. And after drying, seacocks installed:
Next was finishing the clear-coat on the the bulkhead and installing:
And continuing the painting process in the aft cabin:
Cheers,
Mark-san
With the thru-hull backing plate dry, a little paint to make it look nice:
Here checking that the depth of the thru-hulls are ok. And after drying, seacocks installed:
Next was finishing the clear-coat on the the bulkhead and installing:
And continuing the painting process in the aft cabin:
Cheers,
Mark-san
Thanks Rick! It's definitely easier to do things when you don't have to disassemble the boat to get to everything
The new exhaust!
So I finally decided on the simplest approach. Run the exhaust straight up from the manifold to a siphon loop then back down and aft through the lift muffler and out. This solves the giant problem - the water volume from the hose length aft of the engine that would flood the engine due to the location of the factory mixing elbow. But solving a few engineering problems on the way has taken lots of research and parts hunting. The first problem was what to do about the exhaust pipe running up about 2 feet above the engine. It was going to need some heavy-duty bracing to keep from breaking the welds at the exhaust flange. That's where the first solution from the automotive world comes into play (this is the teaser photo from yesterday):
It's a flexible exhaust pipe for a front wheel drive car. Bonus - it's stainless! The idea is to run a rigid exhaust pipe from the manifold about 8" up then connect to the flexible pipe. Then connect to the siphon loop which doubles as the mixing elbow. This will take the stress off the flange and allow for engine vibrations, torque, etc. So after some searching on Summit Racing and Jegs websites, some 2" stainless header pipes show up on my doorstep. Various bends, all mandrel bent. Some measuring, test fitting and fabricating a new flange, and here's the first pipe:
It took some figuring to clear the bulkhead plus account for the mounting angle of the engine (7 degrees nose up) but it fits perfect:
Disregard the dust on the bulkhead, I've been doing a lot of sanding!
Next up, the mixing elbow.
Cheers,
Mark
So I finally decided on the simplest approach. Run the exhaust straight up from the manifold to a siphon loop then back down and aft through the lift muffler and out. This solves the giant problem - the water volume from the hose length aft of the engine that would flood the engine due to the location of the factory mixing elbow. But solving a few engineering problems on the way has taken lots of research and parts hunting. The first problem was what to do about the exhaust pipe running up about 2 feet above the engine. It was going to need some heavy-duty bracing to keep from breaking the welds at the exhaust flange. That's where the first solution from the automotive world comes into play (this is the teaser photo from yesterday):
It's a flexible exhaust pipe for a front wheel drive car. Bonus - it's stainless! The idea is to run a rigid exhaust pipe from the manifold about 8" up then connect to the flexible pipe. Then connect to the siphon loop which doubles as the mixing elbow. This will take the stress off the flange and allow for engine vibrations, torque, etc. So after some searching on Summit Racing and Jegs websites, some 2" stainless header pipes show up on my doorstep. Various bends, all mandrel bent. Some measuring, test fitting and fabricating a new flange, and here's the first pipe:
It took some figuring to clear the bulkhead plus account for the mounting angle of the engine (7 degrees nose up) but it fits perfect:
Disregard the dust on the bulkhead, I've been doing a lot of sanding!
Next up, the mixing elbow.
Cheers,
Mark
The mixing elbow and parts & pieces aft:
Next up was measuring, cutting and welding up the mixing elbow. The brace offsets the elbow an inch from the bulkhead to keep the heat at bay. The brace will be secured to the bulkhead with one bolt in the center - the elbow will essentially swivel, allowing the flex pipe to do its thing. My welder and I wrangled for a while on the angle of the water inlet (he was worried that too acute an angle would make the weld in the corner iffy) so I found a 1" pipe with a J-bend in it so we could have a better inlet angle and still keep the water flowing the right direction:
Next up was how to clamp all the parts and pieces. Again, automotive parts to the rescue. Stainless band clamps!
Now the inevitable question - that's a lot of hot exhaust pipe prior to the water injection! Now what? Again, automotive tech to the rescue. I'm going to wrap the hot part of the pipe in exhaust wrap (and possibly a blanket over that if necessary) and line the bulkhead with Dynomat. Pics of that soon, I just got the wrap in tonite!
With the exhaust in place now down to the base of the engine, I started working from the outlet forward. I debated over keeping the hose loop at the transom and finally decided I didn't need it. Mandrel bend stainless exhaust pipe to the rescue!
This runs forward to a check valve (under the bunk):
I still have to mount the lift muffler and fit the rest of the exhaust hose before I can test it. I have to modify my LM by moving the inlet location then I can get the rest hooked up. Unfortunately, even though I have 29-odd feet of exhaust hose, I might still have to buy some since a lot of the hose is in pretty bad shape. Rats.
I tallied the total cost of all this - half the price of the factory (4 cyl) mixing elbow, and still less than a replacement (3 cyl) mixing elbow that I was going to have to replace anyway. Another bonus is that by using clamps for everything, all the parts are easily replaceable (they are stainless, but 304, not 316, so corrosion might be a factor down the road).
does this look like a valid install, or am I nuts?
Cheers,
Mark
Next up was measuring, cutting and welding up the mixing elbow. The brace offsets the elbow an inch from the bulkhead to keep the heat at bay. The brace will be secured to the bulkhead with one bolt in the center - the elbow will essentially swivel, allowing the flex pipe to do its thing. My welder and I wrangled for a while on the angle of the water inlet (he was worried that too acute an angle would make the weld in the corner iffy) so I found a 1" pipe with a J-bend in it so we could have a better inlet angle and still keep the water flowing the right direction:
Next up was how to clamp all the parts and pieces. Again, automotive parts to the rescue. Stainless band clamps!
Now the inevitable question - that's a lot of hot exhaust pipe prior to the water injection! Now what? Again, automotive tech to the rescue. I'm going to wrap the hot part of the pipe in exhaust wrap (and possibly a blanket over that if necessary) and line the bulkhead with Dynomat. Pics of that soon, I just got the wrap in tonite!
With the exhaust in place now down to the base of the engine, I started working from the outlet forward. I debated over keeping the hose loop at the transom and finally decided I didn't need it. Mandrel bend stainless exhaust pipe to the rescue!
This runs forward to a check valve (under the bunk):
I still have to mount the lift muffler and fit the rest of the exhaust hose before I can test it. I have to modify my LM by moving the inlet location then I can get the rest hooked up. Unfortunately, even though I have 29-odd feet of exhaust hose, I might still have to buy some since a lot of the hose is in pretty bad shape. Rats.
I tallied the total cost of all this - half the price of the factory (4 cyl) mixing elbow, and still less than a replacement (3 cyl) mixing elbow that I was going to have to replace anyway. Another bonus is that by using clamps for everything, all the parts are easily replaceable (they are stainless, but 304, not 316, so corrosion might be a factor down the road).
does this look like a valid install, or am I nuts?
Cheers,
Mark
Personally I think its a great install, and I always try to avoid marine stores for most things. Auto shops or semi tractor suppliers are much cheaper. You will be able to tell how well it works soon enough and adapt accordingly if necessary. Nice work Mark, it's great to watch someone accomplish in three months what would take me three years!
Hmmm...i think i would keep the loop at the transom and not have the big "high rise" at the engine. And get rid of the check valve in the exhaust line. If you had a raw water pump failure, hot exhaust gases can damage a check valve. And its another maintenance item..How would you maintain it? How do you know it's going to do what you want when the occasion presents itself? If it sticks, you have no engine...There is a lot of moment arm in the high rise off the engine. The high rise will not vibrate the same as the engine and cracks etc can occur. I see there is a braided section called flexible exhaust. Not familiar with it but how will it do under engine vibration? It's an automotive part but is it designed to be installed farther downstream in an automotive install? Keep CO going outside...You're doing a fantastic job refurbing the boat. I dont think I can agree with the exhaust system....
Big concern that almost torpedoed the whole idea but I researched lots of powerboat exhaust systems and some of the bigger powerboats have fairly long dry exhaust runs wrapped with fiberglass blankets. I have never used the thermal exhaust wrap (been out of the racing/hotrod scene for a few years) but I talked to a few of my old racing buddies and they swear by the exhaust wrap. They wrap everything - header primary tubes, collectors and exhaust pipes. One guy said that the under-hood and in-car temps are now so low that his driving is what makes him sweat now!
Here's what I bought:
Plus I've been using dynamat for the last few years for insulation and had planned on using that in the engine compartment for noise and heat suppression anyway. I'll extend the dynamat up the bulkhead to surround the exhaust.
Mark