glassdave

iTrader: (1)

you can use either between the sheets of wood although I prefer ounce and a half mat and your choice of resin. I have not had any issues with interlaminate bonding with VE. Gonna hafta call my main tech guy Steve an pick his brain a bit


scarab50 yes you have that right. its either / or but not both at the same time. Your Scarab is poly most likely.

scarab50

thank u for clearing that up also u still don't recommend using composites instead of plywood because of the crush factor read many of your old posts just wondering if u changed your mind on that

glassdave

iTrader: (1)

still not sold on composite transoms on high perf boats (hard use race boats). not saying it shouldn't be done its just im not impressed with the ones I've had. Raced three different boats with BW26 transoms and all developed issues, not catastrophic but issues none the less. Over time with hard use they all flexed at the top and bottom of the drives. Tell ya what though, I am seriously considering doing my Scarab in three layers of half inch just to see how it survives in my real world. I believe Active Thunder builds all woodless and ive always been impressed by their boats, leads me to think I should give it a shot. Keep in mind though, wood transoms dont fail because thier made of wood,

Pwraddr

I have a 37 AT and learned that the transom was composite, and as you said, no wood at all. I am not sure of what the issues are, but as you mention, it does eliminate the possible rot.

scarab50

do u think using composite with expoxy resin would make a difference in flexing problems and how about doing the stringers in composite I guess that is what at boats must do dan archer archer marine says to use a spacers for thru bolts so not to crush the composite that is a lot of work esp on the transom but that is a milatry spec for boats he builds for the government does at boats do all that really tough decision which way to go if u do your scarab with composite would u go thru all that trouble or just mount everything normally I guess ill have to decide soon to beat the cold weather boat is outside thks for any more input anybody has

sparky24

not only could you have problems but wouldnt the materials cost more than 3 times the amount of two sheets of marine ply... It seems like a big gamble just to save a transom from rot, the first wood transom lasted 25 years in your boat why shouldnt the next?

my boat is 35 years old and the transom and stringers werent even all that bad, the transom only had rot between the bottom of the drive hole and the drain hole and a little bit around the exhaust holes. The stringers in mind only had about an inch of rot at the bottom. But that rot did cause significant delamination from all the freeze thaw cycles.

scarab50

just so much work cutting everything out I figured maybe try something different but everyone seems to think plywood is the way to go so I will do that I know it will last my lifetime just always looking for different things to try another day of grinding and ill be ready to start thanks everyone for making up my mind and dan at archer marine ill be in touch soon if u stumble across this thread he is a great guy to talk to about scarabs loaded with info on set ups

glassdave

iTrader: (1)

yes you can build a very stiff and strong panel in epoxy/composite. I am doing a complete build for the USGS at the moment and they demand the highest performance at all levels, its 100% epoxy and Coosa Bluewater. I guess I should clerify my thoughts on composite transoms. Coosa makes a full one and three quarter inch thick panel, thats the one I really dont care for. If I do my Scarab its gonna be three layers of half inch with a layer of 1708 and mat binding each layer together. All three race boats that developed issues were compression flex at the top and bottom, one was a 38 Fountain that had a standard spaced stagger and flexed enough to wipe out a brand new pair of Herring five blades when they hit together during a race.

I agree with Archers method wholeheartedly, sleeve everything. Its time consuming but important with foam.

Coosa BW26 is about two thirty a sheet if memory serves.

scarab50

yeah dave that really sounds like a lot of extra work thru bolting with spacers ill go with plywood but if it wasn't for the advice from u guys I probably would gone with composite but never had known to use spacers hope your build for usgs is t&m tks again

glassdave

iTrader: (1)

its a lot of work to do it proper, and in some cases its warented and necessary to go composite. I'm still old school for the transom, marine ply has worked great for years and will continue to do so. I will say this though, if a budget can handle it composite is great for stringers and bulkheads its way easier to work with has great properties for that application but you do have to use engine mounting methods specific to composite stringers.