Working on the transom

[stefrobrts]

Ok, I am trying to get back to the boat. I'm feeling motivated by the sunshine. So I went out and bought a piece of low-void MDO plywood, which is exterior grade. I got 1/2 inch, and I plan to do three layers with fiberglass mat in between. I'm following the runabout restoration book. I've got West System epoxy a friend gave me. I don't know if it's enough to do the whole job or if I'll have to go get more before I'm done. It should be enough to get started at least.

Tonight I plan to start by cutting out the layers. I have a cardboard template I've trimmed to the shape I need.

triple stack..

Excellent! Are you going to keep it after all?

I have a Lark VI shortshaft that was given to me last year by GregS if you need it to cobble together a runner and have spares...freeeeee!

[stefrobrts]

Yeah, my preference has always been to keep it. Our business has been picking up recently (despite the gloom and doom on the news) so hopefully things will continue to get better. But I figure if things really go in the toilet, and we have to downsize, at least the boat will be more complete and easier to find it a new home where it will get finished. But if all goes well, maybe I can finish it and enjoy it myself!

I appreciate the offer. I have a 61 Lark 3 long shaft and a 65 Johnson short shaft already. I don't know much about boat motors yet. I figure I'll worry about that once I get the boat back together!

[stefrobrts]

Tonight I got the first piece of plywood cut based on the cardboard template I had made. The plywood fit pretty tight so I'm going to sand it down tomorrow until I get it to fit just like I want with room for the mat around it.

[stefrobrts]

I got two 1/2 inch pieces of plywood cut and fitted (need to trim a bit off the top, but the sides and bottom fit well).

But that's only one inch of wood. When I measured the old transom it was 1 1/4 inch, with another 1/4 inch bonded onto the outside/back of the hull. I think once I add mat to the two layers I have now it will fill in the area between the back of the hull, and the fiberglass where the front of the transom used to be.

One inch doesn't seem like enough transom to me. Should I add another layer to the inside, or just go with a layer on the outside of the hull like they originally had? (I included a picture below so you could see where I removed that outside 1/4 inch piece, which had to be removed because it was also rotted through)

I'd love any advice from those who have done this sort of thing before.

One opinion...

Stef- Since you are going to all this trouble it would be great to get your transom built up to 1 1/2 so you can hang a bigger motor later. The inner flange in your picture isn't really helping you, if it was cut away you could fit 3 layers in there. The flange will be easily reproduced afterwards to tie it all back together. Fiberglass mat between the hull and first piece, In between layers I don't see the need for fiberglass mat since it provides little benefit with the mdo you are using. Apply a thin layer of epoxy to each mating surface, when all three layers are in place screw through the outer surface in as many places as necessary to tighten the joint- clamps on top if you have any.

The material you saved can be used to rebuild the flange.

[stefrobrts]

So your suggestion is:

Remove the inner flange

Go with three layers of MDO

Epoxy fiberglass mat between the existing back of the hull and the new plywood

Epoxy the plywood together with no mat between them

Finish it off with a thick layer of epoxy and mat to bond it to the sides

Frankly that sounds easier than what I was planning.

Exactly

You should be able to prune this task from your agenda-pronto...and on to the next.

The mat between plywood layers is only necessary with uneven surfaces, and inferior wood, if you don't have enough material for 3 full layers, in a pinch you can use the partials as the "meat in a sandwich" with minimal structural loss (horizontal seam would be best).

Before glassing the inside to tie the structure together, it is a good idea to fill the gap around the perimeter with "kitty hair" (fiber reinforced filler, available at Napa or hardware stores, since Battleground may not have a West Marine!), Bondo or polyurethane adhesive from a caulking tube will also work. The epoxy will be awesome for the final layup since it bonds so well and does not shrink upon cure like polyester resin...which can warp the hull on the outside, and is seen many times at bulkhead joints that have been retrofitted.

When working with epoxy, make sure that you know the proper ratio (this can be very confusing, since many different Part B's are available) for your hardener and mix well allowing a short dwell time before application.

If your not itchin', you didn't do it right,

Greg

Stef

If the glassing is new to you as well as the product I suggest you get a couple left over pieces and practice bonding them together with the matt and resin. Remember you are going to be glassing a large vertical surface so better to do a small practice part to better get the feel of what you are getting into. Better to find out your mix ratio needs adjusting or you wish you had bought bigger brushes or a good roller now than in the middle of the job.
Also, anyplace you are going to be glassing to bond the new transom in make sure to clean it good and them rough it up with some rough sand paper. I'm constanly hearing that Epoxy should be used for this to get better adhesion and to a point this is true. However, with proper preparation I can make Polyester stick just as well. Barry

[stefrobrts]

Ok, thanks for the advice. I do have enough to make a third solid layer of MDO for the transom, plus scraps to practice on. I'll try out the epoxy and see how it goes. The friend who gave it to me gave me a quick lesson in using it before he handed it over. Unfortunately he moved to Oregon, so he's not around to ask for help. It is West Marine Epoxy with the measured pumps, so hopefully I can't screw anything up there.

I will locate some of the 'kitty hair', we do have a NAPA in town - you're right, the nearest West Marine is about an hour away. I was wondering how I would fill in the gaps at the ends.

This is beginning to make more sense, I think I understand what I need to do. Might get this boat back on the water yet! Thanks!

[Tim_Mattson]

Transom stuff

Stef,
If you want to practice with scraps,maybe use them to double up areas where cleats ,running lights and chocks are mounted to the upper hull shell.I flag these small repairs with bright tape and have them prepped for when I have extra epoxy kicking off and can use it before it starts gelling up.
You can also practice with epoxy under the dash and beef it up so you can pull on your steering wheel without hearing creaking or seiing things flex.
Another tip is when filling the corner gaps before the final woven glass goes on,round the corners with a tongue depressor so you end up with a nice soft contour.Glass will lay smoother and won`t have as many voids as with squared corners.
A Shurform grater or file can speed up clean-up after it firms up,knock down the chunks ,then wait for some more drying before final sanding.
Keep up the effort.......it will be over soon!
TimM

[stefrobrts]

That's a good idea, there are some other areas that need shoring up, and the dash needs a bit of work for sure. I'm hoping to get back to it in the next couple days and get a bit further along.

[stefrobrts]

I got the cutting discs for my dremel and trimmed off the flange. It looks like things might be a little tricky at the bottom where the fiberglass stringers meet the transom. Hopefully tomorrow I'll get my third piece of plywood fitted.

I also have a question: in the splashwell there is a hole that goes into the hull. This is not the drainplug through the transom, this is on the inner wall of the splashwell. When I got the boat it had sat out in the rain and the hull was full of water. I tipped the bow way up and a bucketfull of water drained out of that hole. So I am wondering why is there a hole there when the rest of the floor seems to be fiberglassed solid? It seems to me like that is the only way for water to get in or out of the hole. Shouldn't it at least be plugged unless you are draining it?

[Tim_Mattson]

Holes

Stef,
I`d plug all holes and only drill-out the ones you`ll use.
Alot of extra holes end up channeling water into transoms and I am learning that tipping a hull way up to drain usually only lets the water touch the transom from the bottom,resulting in a soggy transom eventually.
I tip way up for a half day ,then let the belly hold the water if my covers fail.....Also try a vacume on the hole,you may get more.
Any voids need to be found and filled.

Getting drains to actually work is tough as it is hard to ever get a drain tube to be usuable and functional.They have to sit flush on the outside but parallel to the bottom...yet they have to allow twisting or flipping of the drain plug at the same time.
I do like one drain in each corner plus the center one for under decks or a bilge sump if possible.
Flat floors never clean up well so any sump with a drain will keep your muck in a chosen location......put a slotted board over it and you`ll never have to see the grime unless checking your pump.
A wood plug or dowel will make hole filling easier,tape whichever end will drain epoxy out and pull it as it gels.
The extra holes also will leak when backing in the water as the transom gets pushed lower than usual,why upper motor holes also need goo-goo.
Almost done with my Trailorboat floor.....need to post some pics eventually!
Too many projects,not enough time.
TimM