Help with transom fairing

Hello all, first time poster. I am in the process of rebuilding modifying a 1980 Master Marine 28' center console. Orginally it was set up for a single outboard mounted in a transom well. I am converting to twin outboards on a bracket. So far I have removed 2 feet of the top cap near the transom, cut out the inner transom skin and removed all transom wood, installed new laminated plywood core consisting of 3 pieces of 3/4" plywood, glassed in the core using 1.5ox csm mat and 4 layers of 1808 biaxial, and applied numerous layes of 1.5oz mat and 1808 biaxial to the outer skin trying to build it level. I am using vinyl ester resin for everything.

My question is concerning fairing of the transom. The outer transom skin is 5/8" thick, and currently I am within 1/8" of being level. I plan to apply 2 more layers of 1.5oz mat and then begin fairing. Is there a minimum and maximum thickness for fairing compound? I plan on using a mixture of vinyl ester resin, cabosil, and microballons.

Here is a link to the entire project to get an idea of the work. I have also included a pic of the transom to show the major area I will have to fair.

Entire project: http://img5.imageshack.us/gal.php?g=noenginesbutitfloats.jpg

Outer transom pic. Please note that i have cleaned up the excess 1808. I was running out of time for the day and didnt bother trimming the excess since it was the last layer.


Shot with COOLPIX S630 at 2009-06-23

 

Your doing a pretty good job on that boat! Or maybe it's the yellow alien that

should get the credit.Two more layers of 1.5 mat should bring you within range.

My chart says .045 per layer. It depends on if you are using bubble busters

and getting the laminate worked down good. With mat, it won't hurt to have

too much and have to grind it back.


Before you put the deck back down, you should pull the tank and see if it is

still good. They don't last very long, and if the transom and deck were bad,

odds are the tank is on the downhill side.

 

I once confronted one of those that someone had converted to twin outboard on a stainless bracket. It was slower than those with singles, got severely in the way, and was inconvenient for beaching having to lift two ( a great beaching boat, by-the-way, with that deep forefoot, one is held off enough to keep the outboard from touching down without lifting as much ). I converted it back to a single and the guy is much happier zipping around, out-maneuvering the heavier beasts. Got $500 for the bracket. I know these boats well and will peruse your pics when I get time. One thing, for sure, the fuel tank has to come out, the vents, etc. and whittling the foam out is no mean feat. The rubrail has to come off to re-attach the hull to liner.
Less fairing putty is better. Longboard but the outboards will hide slight
faceting of the transom. More scarf would be better. It's not too late to grind the original more and glass over a few layers for ten inches or so. Wouldnt be a bad idea to remove all gelcoat and glass entire transome.

 

Thanks for the replies. Since nobody said anything negative, I am assuming my fairing compound recipe is OK? I am very familiar with the long board. I have done quite a bit of paint and body work on cars and equipment, just not too many boats. The transom wasn't really in bad shape, there was no rot, but it was wet around the thru hulls and drain. The deck was cutout to allow access to inspect the stringers and to make room for an additional tank. The tank will be coming out for sure for a couple of reasons, but it has already been replaced in the recent past, so it should be OK. I am installing an additional fuel tank for greater range and will have to move things around a bit to accommodate both tanks. Secondly, I have done some drilling samples and found the stringers are wet. They are easy enough to replace and while replacing will be raised to deck height for better support.

The rub rail is already off due to painting, but I am not pulling the entire cap/liner off. I only cut the cap at the stern where I need to get to the transom. I cut the deck about 3" from the edges all the way around and will install the new deck on top of the lip that is left in order to raise the floor 1". This will allow me to raise the scuppers and ensure the deck is self bailing.

Mark, do you have more info on the boat you dealt with? I have only found one other converted to full transom, bracket, and twins. He is down in the Caribbean and is running twin 150 2 strokes on a full flotation bracket. I don't plan or need to beach the boat, so that is not a worry for me. This is my offshore boat. I have a smaller boat for playing around inland. Was is one of the open Gil type or early Stainless Marine brackets? Or a fully enclosed flotation bracket? My last boat was also converted and it ran great with the flotation bracket. I have never been out maneuvered by a single engine boat, especially around the docks. I can dock easier and faster than most single engine boats. One engine in forward, one in reverse and it will do whatever you need. I repowered my old boat with 4strokes and never sold the old 2 strokes, so they will provide initial power to get things sorted out and get a feel for how much power and engine weight works best. They are Yamaha V-76 saltwater series II carbed 250s, for a total of 500hp. The newer True World hulls are setup from the factory with a bracket and twin 250s, so it must not work too badly, although they did change the hull slightly.

Sorry for being so long winded

If anyone is interested in following along, I can post all of the pics here and keep it updated.

 

There are something like eight of these here in Alaska. The Moonies have an operation on Kodiak where they used them. The one I rebuilt was rolled in the surf in bad weather. I think the guys got scared of the real ocean and sold off all of the boats. There are now, what, six of them in Homer and have become somewhat of a cult item (fire sale prices, too) for around the bay water-taxis and take more seas than the bay usually dishes out (their main competition is either Hamm hulls or Tollman skiffs - neither of which are much competition really). let me find my pics of this rolled-in-the-surf-trainwreck and I'll figure out how to best post.

 

MAKE SURE THE HULL DOESN'T LOSE IT'S SHAPE WHEN YOU TAKE THE STRINGERS OUT. WHEN YOU PUT THEM BACK IN, YOU WILL LOCK THAT SHAPE IN PLACE.

Don't ask.

 

Mark, i would be really interested in seeing any pics you may have. I have not found too many, other than boats for sale.

SamSam, judging by hull thickness I dont really think that will be an issue, but the bunks on the trailer support it very well. Also I am only intending on removing one stringer at a time. They are not huge stringers or anything. The inner 2 stringers consist of 3/4" x 10" tall plywood wrapped with woven roving tabbed to the hull. The outer 2 stringers are 3/4" x 5" tall and also wrapped with woven roven and tabbed to the hull. My plan is 2 pieces of 1/2" or 5/8" laminated together with the joints staggered to create full length stringers and also raising them to deck height, bedding in resin/cabosil, then fully glassing them to the hul using 2 or 3 layers of 1808. If any of this soungs off base let me know and we can discuss it.

Thanks again for the replies,
Patrick