Transom replacement

[relentless]

I am in the process of replacing the rotted transom in my 89' starcraft holiday 221. I am debating whether to seal the new transom wood with epoxy or paint or just leave it bare. Sealing seems like a good idea, but if it somehow absorbs water it would be much harder for the moisture to escape, causing rot. In my expirience, moisture causes the wood to swell rendering any sealant cracked and useless. The boat won't be sitting outside uncovered or in the water for long periods of time. Has anyone used products other than wood? Just looking for some suggestions/shared experience. And any products that have worked well or flopped.

 

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[Frogger]

Relentless I would do a search on here for past post. Some real good threads on this. I redid mine with a non wood, Seacast. In a nutshell it was higher cost but came out nice. Wouldn't do it in the middle of winter if I were to do it all over. Resins are tough in the cold. As far as protecting the wood, I think it's a must. Not that it's going to get wet from rain and such but just the environment itself will rot the wood quickly. Also the treated wood will cause your aluminum to pit from the corrosive nature of the copper. Coating the wood with an epoxy resin will make it bullet proof. Overall the job is harder on the mind in preparing than it is to actually do it. Hope that helps.


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[muskiedreams]

If you go with wood, you shouldn't use pressure treated because the chemicals used to treat the wood is corrosive to metals. Use a high grade exterior plywood because the glue used between the layers will not delaminate if it gets wet. I had mine done by Clint at Samson Marine (when it was the Watercraft Clinic) in Red Creek, NY. He used resin to seal it and to seal between the pieces of plywood. When I did my floor, I also used resin. The only thing is, the resin I used on the floor must have dried kind of brittle because some areas of the floor that flexed due to poor support got soft and I believe it is because the resin cracked, allowing moisture to seep in. I don't know if some resin stays more flexible to keep that from happening. Also, you need to seal every hole all the way through to keep moisture from entering there. My floor originally had aluminum rivet fasteners, so that is what I used. I pumped sealer into the holes ahead of the rivets.

Edited April 3, 2017 by muskiedreams

[yabmob]

Take a look at Aluthane. I re did the transom of my Starcraft Islander 191 and was going to use epoxy until I found Aluthane from Progressive Epoxies. I bought a gallon and did the transom, the floors on both sides and used it as a primer on the outside of the transom. I have fished 3 years with these floors with no ware on the paint. The stuff is awesome.

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[relentless]

Take a look at Aluthane. I re did the transom of my Starcraft Islander 191 and was going to use epoxy until I found Aluthane from Progressive Epoxies. I bought a gallon and did the transom, the floors on both sides and used it as a primer on the outside of the transom. I have fished 3 years with these floors with no ware on the paint. The stuff is awesome.

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I'll have to check in to that. Not the first I've heard of that stuff.

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[relentless]

I've found that the floatation foam causes some problems! Over the tank in the center, solid as a rock, sides where its filled with foam, soaking wet super mush!

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[relentless]

The foam is like watermelon. I can not believe how much water is soaked up into it.

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[yabmob]

It will all need to be removed. Check the rivetts on the bottom for loose or missing ones. My Islander had a small hole that the foam hid. The cheap replacement is pool noodles. They are a closed cell foam that is great flotation. It is a messy and frustrating job. I used 3/4 exterior plywood from Lowes. I should have stuck with the 1/2 inch. I replaced the foam with sheets of Styrofoam SM and pool noodles. The foam gets saturated because the water has no way to drain to the bildge. If you need more help let me know. The Holiday is an Islander without the cabin. It actually has more usable space on it for fishing. I am considering trading for one.

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[yabmob]

By the looks of your posts, you are on the US side of the Pond. I am on the North side. I had to get the aluthane delivered to a US address then bring it across the border. I am considering getting more.

Yabmob

[relentless]

It will all need to be removed. Check the rivetts on the bottom for loose or missing ones. My Islander had a small hole that the foam hid. The cheap replacement is pool noodles. They are a closed cell foam that is great flotation. It is a messy and frustrating job. I used 3/4 exterior plywood from Lowes. I should have stuck with the 1/2 inch. I replaced the foam with sheets of Styrofoam SM and pool noodles. The foam gets saturated because the water has no way to drain to the bildge. If you need more help let me know. The Holiday is an Islander without the cabin. It actually has more usable space on it for fishing. I am considering trading for one.

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My dad has an islander, same hull, but unbelievable how much more room mine has to fish. Only bad part is that i miss the cuddy for storage. The boat is an absolute animal in rough water. Gonna either buy or make a pontoon type couch seat for storage on the port side. After im done with the floor and transom of course. I have a feeling its gonna float like a cork though now. I pulled one garbage bag of foam out and it was all that 30 gallon bag could handle, 30-40 lbs.

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[bobcat]

I redid the transom on an 88 phantom . all the reseach I did said to use marine grade plywood (not pressure treated) and not to seal. I can't remember exactly how thick it was but I had to get various thicknesses of plywood and glue and screwed them together. Then I cut it out as one piece.

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[fishmaster13184]

3 minutes ago, bobcat said:

I redid the transom on an 88 phantom . all the reseach I did said to use marine grade plywood (not pressure treated) and not to seal. I can't remember exactly how thick it was but I had to get various thicknesses of plywood and glue and screwed them together. Then I cut it out as one piece.

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I did it on my islander last spring, it's 2 3/4" pieces and where the motor connects to the outdrive it gets an additional 1/2" piece of wood. Also I just gave my transom board several coats of oil based paint and left no wood raw, oh and I pre drilled every penetration and loaded the hole with silicone (I think it was 3 tubes)

[Captain Carl Bish]

Let me give you some out of the box ideas. First you can replace the foam, remove it, replace the floor, drill 1 inch holes in the floor about 1 foot apart to pour the new foam back in. It will be good until it soaks again....say 5 years if left outside.... longer than you will have the boat if you store it inside.

 

OR. fill the void with pingpong balls...the objective is only to displace water so the balls will work better than foam and never saturate any additional water can simply drain by.  Archimedes principles of flotation require only dry displacement....foam does NOT make a boat float, it only displaces water. 

 

as for the transom.... I have used wood, wood/epoxy, wood/epoxy and aluminum plate and seacast. If I was doing a starcraft I would do a seacast, or a large cut out plate around the lower unit and simply foam in the space.

 

 

[relentless]

Let me give you some out of the box ideas. First you can replace the foam, remove it, replace the floor, drill 1 inch holes in the floor about 1 foot apart to pour the new foam back in. It will be good until it soaks again....say 5 years if left outside.... longer than you will have the boat if you store it inside.
 
OR. fill the void with pingpong balls...the objective is only to displace water so the balls will work better than foam and never saturate any additional water can simply drain by.  Archimedes principles of flotation require only dry displacement....foam does NOT make a boat float, it only displaces water. 
 
as for the transom.... I have used wood, wood/epoxy, wood/epoxy and aluminum plate and seacast. If I was doing a starcraft I would do a seacast, or a large cut out plate around the lower unit and simply foam in the space.
 
 

The ping pong ball idea may just be genius! But how many friggin ping pong balls would that take? My guess would be more than the world beer pong championships would need x2! They are however fairly cheap in quantity.

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[skach1]

Thought the foam also had structure support too besides floatation

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[rolmops]

When I redid the transom on my 191 Islander I used 3/4 marine grade fir which is a very solid plywood. I took the old transom out and laid it on a big piece of cardboard,took a carpenters pencil and drew a line following the contours of the old transom. That was my blue print. Next, I cut 2 pieces of plywood and glued them together using a 1/4 inch piece of plywood on top and about 12 concrete blocks to press down. The hard part was removing the old transom, but with the help of a cherry picker it came out more or less in one rotten piece. That was after having removed the outdrive and the engine to make things simpler. As for paint. It depends on whether your boat is in the water for weeks at a time, where it is stored and maybe it is a "Trailer Queen" If it is in the water all the time,use a two component epoxy paint to seal it. Use this only if the plywood is exterior or marine grade. Interior plywood will rot inside if there is even one spot where water penetrates. If the boat is dry and out of the water most of the time ,you can use Valspar exterior latex. This stuff is designed for outside walls of out buildings. Your transom is out of the elements so if you use 2 or 3 layers, this is plenty good. Tractor supply also has some high quality outside wood paints that are equally good. Wherever you drill a hole ,make sure that you squeeze  M5200 in and around it to keep the water from penetrating. Instead of drilling holes in the transom for fish finders and such, it is a good idea to put some 1x4 board on the outside of the boat , all your screw holes will be in this board and not in your transom. As for pingpong balls instead of foam, that would make it very expensive  and they would "escape". Foam when properly poured is by far the best also for structural support, although I believe that boats over 20 feet length are  legally not required to have flotation foam.

Hope,this helps.

Good Luck.

Edited April 7, 2017 by rolmops

[yabmob]

The foam is not structural. The Jupitor and Chieftain are of the same size and hull types. They had sheets of foam under the floors. My biggest issue with the pour in foam is that it does not let water flow to the bildge. The foam in these boats will keep them at the surface if swamped. The foam is closed cell. This is essentially mini ping pong balls. Styrofoam SM is closed cell. It is used to insulate basement walls. It won't absorb water. The problem is that it ain't cheap. My Islander has SM on the bottom. This lets any water run past the ribs to the bildge. Pool Noodles also are closed cell. Bought a box of them from Wal-Mart. I sliced and diced them to fill all the voids. I used exterior plywood from Lowes. Marine grade is the best, but it is very expensive. The difference between them is that the Marine grade has less voids in it. I looked at the plywood at Home Depot but it was junk. Looking at the edges, you could see lots of voids. The plywood from Lowes was cheaper and solid. The wood in my transom was 25 years old and untreated. It was rotting on the bottom edges but overall in better shape than I thought it was before I removed it. I laminated the 2 sheets of 3/4 with PL Premium construction adhesive. Once stuck with PL it will never come apart. After shaping and cutting out the key hole I sealed both sides and the edges with Aluthane. 3 or 4 coats. Now the water is unable to sit against the transom because it goes to the bildge. 5400 is great sealant but it is over kill. 4200 is as good a sealant but less of an adhesive. 5400 is considered a permanent adhesive. 4200 cures in 24 hours vs 7 days. Seal everything that goes through the transom. If money is no object, go Marine grade. In my opinion, good fir exterior grade is more than adequate due to the protected locations of our transoms.

Yabmob

[relentless]

The old transom is out and boy is it rotten. I'm thinkin I'm gonna use pool noodles or pipe insulation under the floor. Hopefully that will allow water to flow out and not soak up water. I'm thinkin that that may help to keep the floor dryer. Im probably gonna order the marine plywood for the whole boat but may use exterior on the floor if it doesnt look to bad. The old stuff i pulled up the glue was still sticking like crazy, just the wood was toast.


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[skach1]

What symptoms gave you clues it was a bad transom ?

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[rolmops]

The main reason why foam is the preferred material in spite of all the bad rap it is getting is that it sticks to the bottom of the boat. If you ever are in a sinking boat, you want the flotation material to be sticking to the boat without any empty spaces that will fill up with water before you know it. You do not want material that is loose, because the upward force may very well lift the floor of your boat and then all that flotation material will escape and your boat will sink.

[yabmob]

I can see why that would be a good idea. The stuff sticks like gum to the bottom of my shoe. Imho, the floor is either rivited or screwed in place or both. It should be well fastened due to pounding our boats take on a rough lake. While researching the transom and floor replacement for my boat, I came across the info that the flotation in our boats will keep the boat at or near the surface at best. The difference in floatation between the poured in stuff and the laid in stuff is minimal. If flotation is a huge concern, you could spray foam under the gunnals. The size of the gunnals on these boats would hold a lot of foam. There is a huge section on Iboats on reconstruction of Starcraft boats. It is a great resource to read through. I found lots of info for all the problems I faced when I redid my boat. I have been on Erie with 6 footers and felt totally safe, not comfortable, but safe.

On another note. It looks like there is pitting on the inside of the transom. I used alumiweld from Harbor freight to fill in the big pits and to fill in holes from old transducers and junk that the previous owner had mounted on the back of the boat. Make sure you follow the directions for a good result. YouTube was very helpful.

Yabmob

[relentless]

What symptoms gave you clues it was a bad transom ?

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It was rotten. You could push a screw driver through it in spots. Especially where the foam touched it in the bottom side corners. The floor has a lot of soft spots in it too. Didnt realize how bad the plywood was until i pulled up the vinyl. The foam was actually supporting it. The foam was completely saturated with water as well as the plywood that was in contact with the foam.

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[relentless]

The main reason why foam is the preferred material in spite of all the bad rap it is getting is that it sticks to the bottom of the boat. If you ever are in a sinking boat, you want the flotation material to be sticking to the boat without any empty spaces that will fill up with water before you know it. You do not want material that is loose, because the upward force may very well lift the floor of your boat and then all that flotation material will escape and your boat will sink.

I agree, but foam completely saturated is not helping much either. Especially when it assists in the degradation of your transom which if it fails could cause you to sink. I think the foam starcraft used wasn't much good. Im researching the pour in foam also, just hate to have to do this again. It seems there is not really a good way to do it without spending a ton of money on flooring that cannot rot.

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[rolmops]

Now that you are down to the bare aluminum, you have a good chance to use some "Gluvit on the inside of the hull. You don't have to do the entire thing,just a few dabs here and there where you see suspicious rivets. As for drainage under the foam, You can lay some bubble packaging plastic strips on the bottom and pour the foam on top of it. That will take care of drainage. Just remember that if you spring a leak, the drainage can also work in the reverse direction. The main reason for foam to go bad is not leakage ,but rain. Rain water gets on top of the foam and stays there until winter when it freezes. The freezing of the water causes the closed cells to break up. Do not leave your boat uncovered out in the rain for long periods of time. It is a slow process. I think that the foam has a good track record if you figure that it was put in in 1989 and you replace it in 2017. Maybe it should have been replaced 5 years ago ,but even so.. Foam has an upward force of 60 pounds per square foot and your engine alone weighs 540 pounds (3 liter mercruiser) add to that the aluminum weight and other things that you carry and you can see how you need about 25 cubic feet of foam. Try and buy 25 cubic feet of pool noodles and shove them in the hull, and when water freezes on noodles they also disintegrate because they are made with a short life expectancy in mind.

On a final note. A 28 year old boat that only now has to have its transom and foam replaced, has a pretty good track record. If you fix the transom and pour the foam in you probably are good for another 20 years.

Good Luck

Edited April 9, 2017 by rolmops

[relentless]

True. And i am pretty sure it was left out at least for the last couple years as it sat in a slip. I can see how if you ever puncture the hull the foam would keep the water from pouring in. It was wettest at the transom where i believe the water was coming in around the transducer holes and bolts that hold the transom in.

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