Shawn Fisher

Redoing 2004 Velocity transom. I’m comfortable working with epoxy and 1708. Going back and forth on Coosa or 3/4 marine ply. Wood lasted 20 years and would have lasted longer if some preventative maintenance would have been done. Anyhow leaning towards two 3/4 sheets marine ply laminated together with epoxy peanut butter. Question is do I just seal the side that gets mounted to the fiberglass with neat epoxy or would a layer or two of 2 oz chop mat be better. Would you build the entire transom on the bench including the fiberglassing of the face? PB it in and just come back and tab it in with 1708. I’m leaning towards 3 layers of tabbing 6,9 and 12 inch but open to the most bullet proof approach.

glassdave

iTrader: (1)

going to sit down tomorrow and post up a transom recipe for ya, chillin watching documentaries at the moment lol. Your on the right track but need a few adjustments to the overall plan. My preference on my boats is a marine ply transom but three layers of half inch instead of two layers of three quarter. Wood transoms do not rot simply because they are made of wood. They rot for many other reasons including poor care throughout its life and bad instalation/workmanship. I dont care for how flexible composite transoms are and the whole myrid of problems that come with it. Anyways . . . i'll pop back on tomorrow and shed more light. Im not against Coosa transoms they just need to be installed as such, certain care needs to be taken in certain areas (in high performance applications)

Shawn Fisher

Was hoping you were going to chime in. Thanks

Rookie

iTrader: (4)

I fixed it for you...

Wildman_grafix

Funny, glass Dave is not the first that have said that about Coosa transom's.

jeff32

you are late to the party!
we are waiting to hear you !
😂

Shawn Fisher

What do you have for me GlassDave 😀

glassdave

iTrader: (1)

okie dokie kids i'll see if i can get the ball rolling on my thoughts.

Coosa vs wood - i personally prefer wood on my boats, coosa can be flexible and has its own set of potential problems if not done correctly. Wood does not rot simply because its wood, it rots for any number of other reason like bad install or poor lifetime care to name a few. Heck i could probably do a transom in OSB in a way that would outlast many mid level factory built boats For starters composites or Coosa cannot be installed as simply as you'd install marine ply, at least not for our high performance applications. You really need to be aware of point loading of all potential areas like the tops of transom assemblies and trim tabs where torque forces the edges to dig in. Ive have to replace failed composite transoms that were maybe ten years old because the point loading crumbled the foam and "eyebrow" cracked the surfaces. If im doing composite transoms i use three layers of half inch Bluewater 26 or 32 with a full lamination of 24oz roving between each layer (about the only time i ever use roving) While Coosa allows you to build lighter i tend to use that weight savings and stack more surface laminations on the inside to help stiffen up the final product and i may stagger a few layers of roving in as well, really just depends on if its a high HP number six boat of an XR boat. If your going through the effort to use advanced materials you'll want to carry this theme throughout. That being vinylester at the very least, you "can" use poly but i would not under and performance application, i also dont feel it bonds worth a damn to any foam. I prefer to use 1700(no mat) bi ax over 1708(w/stitched mat)bi ax but this is also dependent on whatever im building. At much of the DIY level i would recommend 1708 as its much easier to handle.

epoxy vs VE - again this is dependent on what im building. 90% of my work is VE and epoxy is reserved for Skaters and the like (anything OEM built in epoxy). Many may not know that VE is still an epoxy, its just suspended in a styrene rather then an amine (or some techy thing like that) buts still and epoxy and offers physicals that are vary close to a full epoxy anyways. Polys weakness is that it has very low elongation and this causes the molecule to stress, strain and fail at a very low percentage. For arguments sake maybe 1.5% while VE can stretch up to maybe 5 or 6% and a full epoxy 7 or 8%, not exact number but you get the point. Consequently i dont often feel a full epoxy is necessary on some of our older boats but if your comfortable using it theres no down side really other then epoxy is very intolerant to less then perfect workmanship. VE offers many of the advantages of epoxy and is workable in a much more familiar method to the DIY guys. Plenty of pros and cons to each, epoxy can give you some loooong work times which is nice sometimes.

I will add some more to this later and as long as i've been in this biz there are many ways to do things these are just some of my preferences

Shawn Fisher

Thank you sir look forward to more details. I’ve since been leaning hard to wood. Would love to see recommendations on wood and layup schedule.

glassdave

iTrader: (1)

most any quality marine ply is fine just make sure its rated as marine and not just outdoor ply. A lot of guys think outdoor is acceptable but it most certainly is not. Pine has oils in it that affect surface bond douglas fir does not.