How to reinforce transome

[Rich]

Hey guys. I wanted your opinion on how to reinforce the transom on my MHZ Oceanspray hull. I put a layer of carbon fiber on it a year ago and I still think it needs more. I haven't gotten around to messing with it until now. Should I just but another layer on it or make an aluminum plate or use wood?

Thanks for your help.

Rich

[1coopgt]

This question doesn't matter. What makes you think you need to add more reinforcement to your transom. Just curious,

[fweasel]

I use 2mm carbon fiber plate to reinforce transoms on nearly every V-bottom hull I build. I scuff up the mating surfaces with very coarse sand paper on both the plate and the hull, wipe down, and glue in place with epoxy. I clamp it in place while drying, if I can. If not, I set the hull up vertically and use heavy metal machining blocks to weigh down the plate as the epoxy dries. I will often clean up the edge along the bottom of the CF plate with a bead of dyed epoxy, using it like bathroom caulk.

IMG_20200517_161930.jpg

[Bande1]

I used a .060 sheet of aluminum from the hobby store, made a paper template. I think it looks cool.

[Rich]

This question doesn't matter. What makes you think you need to add more reinforcement to your transom. Just curious,

I think it does matter when you need rigidity to keep the rudder and other stuff from flexing under load. My hull needs more rigidity since its a lot of mass to move.

I use 2mm carbon fiber plate to reinforce transoms on nearly every V-bottom hull I build I scuff up the mating surfaces with very coarse sand paper on both the plate and the hull, wipe down, and glue in place with epoxy. I clamp it in place while drying if I can. If not, I set the hull up vertically and use heavy metal machining blocks to weigh down the plate as the epoxy dries. I will often clean up the edge along the bottom of the CF plate with a bead of dyed epoxy, using it like bathroom caulk.

fweasel, that looks really good! Hmm aluminum would look good too. Not that anybody will see it.

IMG_20200517_161930.jpg

I used a .060 sheet of aluminum from the hobby store, made a paper template. I think it looks cool.

Bande1 I have some aluminum laying around maybe ill go that route.

Thanks guys I like both ideas. I am laying carbon on the bottom of the hull now. I will use one of your ideas.

[1coopgt]

Hope you don't think I meant your question. I meant my question.

[Rich]

Hope you don't think I meant your question. I meant my question.

That makes sense now, I did think you meant my question.

[tbonemcniel]

I've used carbon fiber plate to reinforce a number of transoms. I cut out a template from a cardboard box, then cut out the plate from that, and epoxy it into place.

[T.S.Davis]

I use aluminum plate on every transom. Then I drill and tap for the hardware because I hate hate hate trying to mess with nuts in there. It's always a PIA.

That is unless of course......I'm too lazy to do it. It happens. I've built a lot of boats.

[Peter A]

What I have done on many boats is cut a piece of carbon cloth to fit inside the transom, stand the boat up on it's transom and fill it with epoxy resin enough to cover the cloth. By standing the boat flat on the transom this gives a nice flat surface inside and extra strength. In hard to get to areas I will also glue in some 3mm ali plate and drill and tap.
This system works really well if it is a used hull and you are re doing hardware. Just tape over all the holes and allow the resin to fill them up.

[Rich]

Thanks guys for all of the suggestions! I'm thinking about going the aluminum plate route and maybe drilling and tapping it because I too hate dealing with nuts! On the other hand though this is a larger hull (mhz ocean spray) so I will have plenty of room to get a socket in there to tighten the nuts.

[T.S.Davis]

Thanks guys for all of the suggestions! I'm thinking about going the aluminum plate route and maybe drilling and tapping it because I too hate dealing with nuts! On the other hand though this is a larger hull (mhz ocean spray) so I will have plenty of room to get a socket in there to tighten the nuts.

If you have the room carbon wont add much weight. G10 would work too. Cheaper option.

The nuts that I find most annoying are the turn fin brackets on smaller boats.

[Rich]

If you have the room carbon wont add much weight. G10 would work too. Cheaper option.

The nuts that I find most annoying are the turn fin brackets on smaller boats.

Maybe I'll go with carbonfiber since it will save some weight. How do you guys go about cutting the carbonfiber plate?

[Bande1]

Maybe I'll go with carbonfiber since it will save some weight. How do you guys go about cutting the carbonfiber plate?

you can just lay the CF on the transom as another layer. If you want a plate make a template from cardboard.

[fweasel]

Maybe I'll go with carbonfiber since it will save some weight. How do you guys go about cutting the carbonfiber plate?

Cover the carbon plate with painters tape, trace your paper template onto it, then cut with a dremel cutoff disc or a diamond bandsaw blade. I use a diamond dust cutoff wheel from dremel for most cuts, my bandsaw for long cuts, and trim to fit with my bench belt sander. I use a HEPA vacuum to capture the dust while cutting and I wear a mask. CF dust is nasty stuff.

[T.S.Davis]

You can cut carbon with regular band saw blade but the blade will be useless after. Just gobbles them up.

[fweasel]

You can cut carbon with regular band saw blade but the blade will be useless after. Just gobbles them up.

I've had good luck with the diamond dust blade, no teeth, just the friction surface.

[dasboata]

You can cut carbon with regular band saw blade but the blade will be useless after. Just gobbles them up.

yes it does sparks like steel at times CF is some tuff stuff,, I use 2" reinforced cut off wheels with a vacuum , pretty easy to hold a straight line after you get it going

[T.S.Davis]

I've had good luck with the diamond dust blade, no teeth, just the friction surface.

Begs the question.......why have I never bought one? WTH Davis?

[Rich]

Thanks guys lots of good info here. Where is a good place to buy carbonfiber plate?

[fweasel]

Thanks guys pots of good info here. Where is a good place to buy carbonfiber plate?

Depending on the size of the part you're looking to make, I usually buy these from OSE: https://www.offshoreelectrics.com/pr...prod=ose-82044

If I need bigger, or thicker, I get them from eBay.

[Rich]

Depending on the size of the part you're looking to make, I usually buy these from OSE: https://www.offshoreelectrics.com/pr...prod=ose-82044

If I need bigger, or thicker, I get them from eBay.

Thanks! I'm going to need bigger than that. I'll have to look around.

[Rich]

Thanks! I'm going to need bigger than that. I'll have to look around.

I bought my carbon plate. I got on about 15"x15" for 62 bucks 3mm. It looks good. It should do both my larger hulls. Anyway, how do you guys go about filling holes you don't need in a transom? I have a boat I have been doing some testing on and need to fill holes. Do I just tape them and fill with epoxy?

Thanks,
Rich

[fweasel]

Yep, mask the holes off from the outside and fill from the inside with epoxy. I try to fill them slowly and do a little prodding with a toothpick to make sure there are no air pockets. If the holes are just in random spots, I use regular epoxy. If they're close to where new holes are going to be drilled for drives or rudder mounts, I'll used JB Weld which is a little harder when cured so the drill bit won't drift as much when drilling the new hole through the patch.

[Rich]

Yep, mask the holes off from the outside and fill from the inside with epoxy. I try to fill them slowly and do a little prodding with a toothpick to make sure there are no air pockets. If the holes are just in random spots, I use regular epoxy. If they're close to where new holes are going to be drilled for drives or rudder mounts, I'll used JB Weld which is a little harder when cured so the drill bit won't drift as much when drilling the new hole through the patch.

That's how I have been doing it. It's good to hear others do it that way as well thanks for the info!