1972' Aquasport Seahunter 240 Rebuild

[RickK]

There are quite a few 240 rebuilds in this form, not a ton, but enough to see what others have done.

[Ulysses485]

There are quite a few 240 rebuilds in this form, not a ton, but enough to see what others have done.

RickK,

I thought i would be able to gather some info but i have scoured each of the threads individually and have not found enough information regarding the transformation of the transom. I do remember seeing a few 222's that were completely cut out but not sure what support was used to keep everything square.

[mshugg]

Below decks nearly every Aquasport is constructed the same with trapezoidal Foam filled fiberglass stringers and the voids outside of the stringers filled with foam that expands up into the liner.   That means that nearly every rebuild, no matter what model, provides useful information.

As for maintaining shape and square, make sure the hull is well supported.  This can be on a trailer, boat stands or a custom cradle.  After that, the key is to be thoughtful about removing structure.  For example, if your stringers are in ok shape, even if you’ll need to replace foam or re-tab sections, leave them in until after the transom is repaired.  Similarly, it is easier to maintain shape if you keep one of your transom skins intact while you rebuild the transom.  The outside skin is thicker than the inner skin, so in most cases it’s better to rebuild from the inside, even though that requires cutting away the aft 18” or so of your stringers and deck.

[Ulysses485]

Below decks nearly every Aquasport is constructed the same with trapezoidal Foam filled fiberglass stringers and the voids outside of the stringers filled with foam that expands up into the liner.   That means that nearly every rebuild, no matter what model, provides useful information.

As for maintaining shape and square, make sure the hull is well supported.  This can be on a trailer, boat stands or a custom cradle.  After that, the key is to be thoughtful about removing structure.  For example, if your stringers are in ok shape, even if you’ll need to replace foam or re-tab sections, leave them in until after the transom is repaired.  Similarly, it is easier to maintain shape if you keep one of your transom skins intact while you rebuild the transom.  The outside skin is thicker than the inner skin, so in most cases it’s better to rebuild from the inside, even though that requires cutting away the aft 18” or so of your stringers and deck.

Hey Mshugg,

Staging my build is my plan to keep a structural form by either the transom or the stringers. Regarding the transom, it’s quite different than the normal 170-222s that I have seen with a standard notched 25” transom. See below photo of what I am dealing with for better understanding of my transom situation.



The center section is about where flush would be so at a minimum I would need to cut the sides out (because they flare away from the back of transom) but still can’t figure out a glass schedule in that situation. Not sure that I am making sense with that statement. I will get a better photo explaining it.

[mshugg]

You can still keep the outer skin, you will just need to fit the first layer to angled profile.  You would build the core out to level and then use flat pieces to build the transom  out to your desired thickness.  This would require some carpentry skills that are a level above basic, but IMO would be less involved than cutting out the skin.  Thickened resin could fill minor gaps.  If you’re going with a bracket, you would need to template the profile, but companies like Armstrong build brackets for more complicated transoms all the time.

If you want a flat transom, because you prefer the look, you would need to screw 2x4s accros the top of the transom before you cut out the skin.  It would be a good idea to take diagonal measurements from gunwale to chine.  They should be equal.

Personally, I like the transom kick out. It reminds me of classic Conchs, Whitewaters etc.

[mshugg]

Depending on the amount of relief in your transom, another option would be to build the transom out to flat with layers of glass.

Here’s an example in an episode of Ship Shape TV(I know.  Too much hawking of product for me too).  They’re rebuilding the transom of a small Whaler that has a similar kick out using Coosa, and they use glass to bring the transom to level enough to bond in the Coosa. 
https://youtu.be/WZWnGLRW0Yk

[Ulysses485]

To hopefully provide some clarity with the different style transom these 240s came with, I have taken some photos during some demo of the rotted plywood transom and marked up some photos along with a really quick sketch of the proposed installation to create a flat transom. During the demolition, i discovered that the corners were filled with foam (creating a flat condition) and a layer of glass over them for the original plywood to bed to. See photo below:


I wouldn’t think the same structure would apply to 550lb motor hung approximately 24” back off the end of the transom so the foam filled corners just doesn’t cut it for me. With that said, i either find a filler material that doesn’t weigh a ton or approach the following plan:

Step 1: glass the flush center section of the transom to a core and core to hull sides/bottom.
Step 2: cut transom corners and taper to accept new tabbing.
Step 3: fair the back end like a son of a gun.



You can see in that photo where the core material (coosa) would sit.

This is a sketch of what I am thinking. My only concern is how strong the bong is with old/ new glass at the outer skin hull sides. I dont like the idea of breaking the hull mold outer skin bond but i don’t like how the corner doesn’t provide much structural integrity.


Thoughts?

Thanks everyone!!

Ulysses

[mshugg]

Wow!  That’s different than I expected, definitely an interesting design feature.  I can certainly see why you would want to rebuild with a flat outer skin.  Another option, if you wanted to preserve the bump outs would be to go with your plan, out in the coosa, and fill the outer areas with pour in transom material like Seacast or Arjay.

[Tampa Bay Mike]

Arjay 6011 was my first thought too. You could also fill it with some scrap pieces of coosa and taper the edges down to fit pretty well. I've also seen 16lb density foam that may work.

[RickK]

My $.02 - since you're not happy with the bump out because you're going to go with a 24" bracket of some kind, I would cut off the bump outs (like you drew) and everything except 2" of the bottom of the old transom skin, lay melamine across the transom and rebuild from the inside. It'll be nice and flat due to the melamine. You'll have less fairing to do on the outside this way also.

[wingnut]

If you do end up leaving the bumpouts, you could go go straight across with the Coosa then fill the voids in the bumpouts with pourable transom compound (poured from the top after installing flat Coosa). It would be crazy strong and wouldn’t add too much weight.

[Ulysses485]

Haven’t really made a decision at this point but i am leaning towards keeping the outside skin, adding a few layers to the insides and laying coosa/pouring in bump outs. Getting into laying glass might make me change my mind but time will tell. You can see here the rough angle a little better. I think if I lay coosa where the old ply was, tab it to the hull sides, I might able to cut the angles section out if I choose to and tab/taper glass on the outside skin creating the flat transom. However, the midsection or the existing transom doesn’t seem to be in line with the transom corners so that will make it tricky.



On another note, I enjoyed my new toy the good ol flap disk. Boy does that thing remove material in a hurry (it also didn’t wear down as much as I thought it would....comparable to same grit rotary sanding disk) I chipped at it in past weekends with chisel and was really encouraged with the flap disk. There is some thick filler that I was not expecting on the inside transom skin.



Naps are a great time to run out and get some work done. He will soon reap all the fruits of dads labor, :)


My plan is to do some practice with the 81’ 22-2 fuel hatch and center console mods this weekend with some poly and once we get that running, I’ll get back on the 240. Give me some time to plan and hopefully fish while I build.

On that note, thoughts on poly vs epoxy for structural stuff like stringers and transom? I plan to Gelcoat just about every surface in the boat hence the lean towards poly. I hear vinyl is stronger, comparable with gel, more expensive but extremely sensitive to temps and MEKP ratios (needing to be in the 2-3% ratio).

Thanks for following along.

Ulysses

[mshugg]

Wow!  Two boat projects at the same time!   

[RickK]

The best secondary bond is epoxy by far - so for structure I used epoxy. Everything below the deck was epoxy, everything above was poly. The bad part about poly is it starts hardening the second it is made, so if you buy a 5 gal bucket, be prepared to use it quickly and hopefully your source of poly has fresh stock. I have no experience with vinylester.

[Ulysses485]

Wow!  Two boat projects at the same time!   

Check out my recent post. Kinda makes it 3  but the 81' 222 isn't getting rebuilt, just modified. Promised the wife it will get sold once the 71' 222 Flatback is done.

The best secondary bond is epoxy by far - so for structure I used epoxy. Everything below the deck was epoxy, everything above was poly. The bad part about poly is it starts hardening the second it is made, so if you buy a 5 gal bucket, be prepared to use it quickly and hopefully your source of poly has fresh stock. I have no experience with vinylester.

That's what i gather but worried about making the transition at the hullsides and transom. I plan to have a "liner" by means of adding 1/2'' foam sheets to the hullsides but not sure i can epoxy the backside to the hullsides and lay laminated glass over the the frontside for it to be gelcoated. I guess i can live with a painted bilge but not sure on the rest. Thoughts? 

Thanks for the input guys! I really do appreciate it.