Raising transom

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Ghostryder65

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Hello everyone. New here. I have been reading lots of threads here. Great group full of knowledge. This is my first question of will probably be many..lol
My transom was rotted so making a new one. Also removing benches and adding a floor and supports, as well as foam under the floor. My question is can I raise transom since I already have 2 long shaft 15 hp in the garage? My plan is to make the new transom without the cutout. Taking the bottom down between and past the 3 supports. Adding maybe 14-16 gauge aluminum to both sides of the wood. 2 part epoxy will be used to build it. A couple extra through bolts for bottom extensions. I believe that will handle the 25 hp that is planned for later also. Thoughts or advice? 197? Mirrocraft 14'
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I think your plan sounds good. Use quality epoxy and quality plywood. What thickness ply are you considering? Be sure to coat inner plywood holes with epoxy wherever you use through bolts.
I plan on using West Systems 105, possibly Total Boat if I find it at a discount. 3/4 Marine Plywood x2 epoxied together, then 14-16 gauge aluminum epoxied to both sides. I plan on pre-drilling all holes before assembly, then slightly enlarging the holes in wood and soaking thinned epoxy in the holes so it soaked into the wood.
 
Doubled 3/4" plywood, with aluminum skin is how I would go, since you need to replace the transom anyway. Good plan and welcome!
 
Would that little bump though get your prop where it needs to be? Pretty sure they make an adjustment plate for just want you want to do. Might be smarter and simpler than to hack up your boat into a configuration that might not work well with any motor.
 
I plan on using West Systems 105, possibly Total Boat if I find it at a discount. 3/4 Marine Plywood x2 epoxied together, then 14-16 gauge aluminum epoxied to both sides. I plan on pre-drilling all holes before assembly, then slightly enlarging the holes in wood and soaking thinned epoxy in the holes so it soaked into the wood.

I'm not following what you mean when you say the aluminum will be epoxied to both sides.
 
I'm not following what you mean when you say the aluminum will be epoxied to both sides.

I wouldn't think that would be a good idea. A barrier coat on each, but not epoxied together. Also, not sure of using it to laminate the two 3/4" plywood. I'd see if it is recommended for that or not. I just used Titebond III.
 
Would that little bump though get your prop where it needs to be? Pretty sure they make an adjustment plate for just want you want to do. Might be smarter and simpler than to hack up your boat into a configuration that might not work well with any motor.
Yes that would put the prop at the correct height. I'm not "hacking up" the boat. Transom needs rebuilt anyway. I already have a selection of long shaft motors, so raising the transom works for me. Once done any long shaft will fit.
 
I wouldn't think that would be a good idea. A barrier coat on each, but not epoxied together. Also, not sure of using it to laminate the two 3/4" plywood. I'd see if it is recommended for that or not. I just used Titebond III.
I have researched it pretty well. The epoxy will permanently join the wood and aluminum skins without doubt. I briefly considered titebond 3, but will be using the epoxy anyway to seal the wood anyway so no need to buy a different adhesive.
 
I have researched it pretty well. The epoxy will permanently join the wood and aluminum skins without doubt. I briefly considered titebond 3, but will be using the epoxy anyway to seal the wood anyway so no need to buy a different adhesive.

OK, I never looked at using the barrier epoxy coatings for structural duty. Titebond III is cheap nd has a good working time.

Keep an eye on the thickness with the lay-up of pywood, epoxy, and skins, that it doesn't create a too tight situation of installing the new transom.
 
I have researched it pretty well. The epoxy will permanently join the wood and aluminum skins without doubt. I briefly considered titebond 3, but will be using the epoxy anyway to seal the wood anyway so no need to buy a different adhesive.

I am in agreement epoxy is superior to Titebond III. What I'm still not clear about is gluing the new laminated transom to aluminum skins. Do you mean you will glue the transom to the inside of the existing transom skin? And then glue another aluminum skin on the inside of the transom wood? I'm just not following and of course curious.
 
I agree with your adjusting the transom height. Will make the boat more useful and seaworthy.

As far as epoxying the skins to the core, does your transom currently have an inner skin?

1. If not, adding one to the inner side is good.
2. If it does have an inner skin, I probably would not add a second skin to the transom core. Moisture will get between the layers of aluminum and cause corrosion
3. But even if you do, I would NOT epoxy it to the outer skin of the boat's transom.

IF you feel that it's just better to fabricate it together with aluminum skins, I would just use marine silicone to install, not epoxy. Make sure to seal the perimeter carefully to prevent moisture from getting in.

Either way, that's going to be a lifetime transom, as long as you are careful to seal all fasteners carefully.

It's your boat, and you have the joy and freedom to do it YOUR way. It will be fine no matter what you choose. These are just opinions and suggestions you are getting here.
 
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Yes that would put the prop at the correct height. I'm not "hacking up" the boat. Transom needs rebuilt anyway. I already have a selection of long shaft motors, so raising the transom works for me. Once done any long shaft will fit.
Will they though? I don't know much about long shafts, but are they all the same? Isn't the cav plate height pretty critical for proper performance? I get why you want to do it, but think I'd be going off what my tape measure tells me which may not be the same as the transom height if you simply remove the cut out. Then again I could be all wet!

My other concern is would it be hard to sell a boat this size that won't take a shorty? That's why I was wondering if a jack plate might be a better idea.
 
If he makes it the right height, (@20" vertically) it should fit any long shaft motor. But you make a good point about the tape measure.

Depending on the rake or angle of the transom, the actual transom board will usually measure longer. The more rake, the longer it will be, but it's the actual vertical height that matters. With little tin boats, height is not as critical as it is with a high-performance boat. So typically, only big, fast aluminum boats have jackplates.

Around here, (Mid-Atlantic area) only the smallest boats, typically 12' or shorter, are sold with short transoms. You will see a few older 14' with a short transom, but a 16' with a short transom is pretty rare!

It seems to me that near big water, 20" transoms are most common in aluminum boats. That is probably why Ghostrider65 only has long shafts available in his area. When it gets rough, that 5" of freeboard may mean the difference between getting back to dock safely or not. I've been there/done that, and don't want to do it again!
 
That's interesting. I'm a long way from the salt, but around here pretty much all small boats, 14' and under, are set up for short shafts. You almost can't give away a long shaft motor of modest HP.
 
I agree with your adjusting the transom height. Will make the boat more useful and seaworthy.

As far as epoxying the skins to the core, does your transom currently have an inner skin?

1. If not, adding one to the inner side is good.
2. If it does have an inner skin, I probably would not add a second skin to the transom core. Moisture will get between the layers of aluminum and cause corrosion
3. But even if you do, I would NOT epoxy it to the outer skin of the boat's transom.

IF you feel that it's just better to fabricate it together with aluminum skins, I would just use marine silicone to install, not epoxy. Make sure to seal the perimeter carefully to prevent moisture from getting in.

Either way, that's going to be a lifetime transom, as long as you are careful to seal all fasteners carefully.

It's your boat, and you have the joy and freedom to do it YOUR way. It will be fine no matter what you choose. These are just opinions and suggestions you are getting here.
Definitely not epoxying transom the the hull skin. No sir, there was no inner aluminum skins in the transom wood. Just the hull. My thinking is that if I bond 14-16 gauge aluminum to either side of the new transom wood, it will help distribute the load more evenly and prevent clamps, rivets, ect from opening the wood to moisture. The may be a 25 HP hanging off of it in the future.
 

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