Re: Original transom does not meet flush with hull.what to do with new transom templa
the black sprayed on foam is so old it flakes right off,I believe all it was used for was sound deadening/vibration. You can see in the new pic as I progress with tear down that the original glass was just overlapped onto the side hull walls,I wouldn't consider that tabbing where you would typically tab in at least 4 inches.Here,it only overlaps a few inches,if that,and absolutely no filler.
After researching many forums etc...the easiest and most cost effective way for me to do this,and I've combined other ideas as well is to do the following,and I'm leaving out some minor details;
1 cut my transom after making template and mark the starboard and port sides accordingly.
2 drill out the water outlet hole and the 4 motor mount holes.
3 cut 2x4s to adequate length that will cross the motor mount holes/water outlet hole for sandwiching/glueing the transom wood together before i set it,making sure to drill the bolt holes in the 2x4s through the TALL side ensuring better lateral support. use 1/2" all thread will work fine with some nuts and washers.
4 I am using polyurethane glue instead of mat or resin putty mix to bond the 3/4" marine plywood together.easier,cleaner,cheaper.once the motor bolts are in its not going anywhere.
5 polyurethane the transom plys together using notched spreader.clamp it using my pre cut and test fitted bolts and 2x4s.let it cure overnight.
6 Encapsulate/waterproof the transom using 1.5 oz chop strand mat.start with one side overlapping egde to meet with other sides leading edge,let it cure to tack free,flip it and repeat so you end up with 2 coats on the edge. let it harden overnight.
6 mix good amount of poly resin/cabosil/chop strand fiber to peanut butter consistency and apply liberally to face of hull skin.moving quickly apply the same mix to the rear face of the transom and affix to hull skin.
7 Clamp securely with your pre cut and test fitted 2x4s/bolts. The part I like about this is the clamping pressure will squeeze out putty into your filet areas giving you an adequate head start on filling.
8 moving fast still i will now fill that transom gap(which i have painstakingly reduced) with the current mix,or a if that is setting too fast i will have my son mix me a new batch of putty to fill with before i complete my putty filling and radiusing stage.
9 I will us a simple spoon to radius the putty to hull walls.
10 I plan on using 1708 biaxial to tab initially,not sure how many layers,probably 2.
11 I will now glass the whole face of the transom 3 times using the 1708 cut to 4" tab overlap for the first layer.Cut to 8"overlap for the second.Then cut to 12"overlap for the third layer.After each layer is tack free I will sand/feather into hull wall,this will promote better adhesion and strength for the next coat and look smoother.
My biggest indecision is whether to use epoxy resin or poly resin on the 1708 glass.I know you can use epoxy resin over the poly resined transom, but the epoxy is much more expensive and requires more work wetting it,which i dont mind,i'm already in it. Also,going over everything with epoxy resined 1708 will hold up better considering this is the top coat that sees all the abuse,weather,sun etc...poly resin doesnt hold up like the epoxy so why not have that peace of mind is what i'm thinking. but the cost factor is getting higher...I dunno.
I did go with standard marine grade 3/4"(cost me78 bucks sheet at local lumber yard,they get it from georgia pacific at no delivery charge to them or me)after reading gobs of pros and cons between standard marine grade/BS 1088/AB exterior/pressure treated/CDX etc...keeping in mind I have a relatively small boat,19' with a big/heavy 175 horse johnson. I weighed all the possible cons of the lesser grade plywoods including;lesser plys,more knots,voids,valleys,warps/trueness issues,scrap pieces added,etc...and the fact that the attention to detail and how they are assembled is typically less. Considering all the work that I am putting into this,I want to reduce failure and risk now and looking at the longevity piece too. For me,investing a little more to ensure a more solid and safer transom build for myself and my children is worth it.
Thanks guys for any and all input.