80's supras - motor mount blocks

[bsampson]

I have a '86 saltare that I am replacing the floor in... Which then led to replacing stringers as well. Lots of rot.

This boat did have the motor mount blocks replaced by a marina by the previous owner. I've noticed they used 4x6 treated wood, then fiberglassed over the top of it.

How should those 4x6's mounted to the bottom of the boat? Adhesive only? It looks like they are attached with some of the same adhesive I've chiseled/scraped away in other parts of the boat. It dries hard, white, and somewhat pourous.

Are these ok "stand alone", or should I try to tie them into the main stringers I'm adding for additional strength?

[Salty87]

i just got the top cap put back on my 87 saltare yesterday, riveting it today. i don't envy you, haha

for both the mounts and stringers, you want to keep the wood a fraction of an inch above the hull. you don't want the wood and fiberglass to touch or you could get a hard spot. if there's any force applied to it, the glass and wood don't flex at the same rate and could result in damage to the fiberglass. that's the theory.

are you using poly resin or epoxy? the common method is to thicken the resin, i used poly. you can add a product called cabosil (there are other options, of course) to the resin to make a thicker consistency, referred to as peanut butter. slop that under the mounts and stringers filling in any gaps from the wood. you'll also want to fill-in the corners created where the hull and stringers meet, called filleting. this helps you wrap them in fiberglass later. otherwise, the cloth won't make the corner and you'll get air pockets= no good.

i had trouble telling what had originally been used for my mounts. it was all mush. i used 4x4's (pressure treated but months old and not wet at all). i notched the stringers to overlap the mounts by about 6-8 inches at the front and back. glassed all together of course.

[bsampson]

Thanks for the tips Salty. I've seen the pics you posted, and I was inspired :)

I'm not pulling the cap. I know I should to do it right, but the project is already much larger than expected, and I only have so much free time. When I cut through the fiberglass wrapped stringers, I kept going until the wood was solid, and stopped. Since I'm not pulling the cap, I can't replace the bow portion of the boat, but luckily, all the wood seems solid up front.

I'm probably keeping 75% of the outside stringers. I'm replacing the bad portions with 3/4" treated plywood, then will scab pieces on each side of it, and glass over the entire piece. I know treated wood isn't ideal, but I came across an article by the APA that stated treated wood should be kiln dried after treatment, and prior to fiberglassing, BUT adhesion is still pretty good even if there is some moisture in the wood. Usually the wood fails prior to the bond between the wood and fiberglass. So, I'm giving it a try on the stringers at least.

I'm using Poly resin. I'll look into a thickener to make some butter. I wasn't aware of the gap between stringer wood and fiberglass, but it sounds like a good idea. I'll do it!

For the floor I'll use 1/2" plywood, but not sure which of 2 routes I'll take. 1) Standard treated plywood coated with poly fiberglass resin or 2) Exterior sign plywood with exterior glue, but a smooth, paperlike "paintable" surface that should soak in the resin a little better, but the wood isn't treated (or I don't think it is..).

[Salty87]

i used marine plywood but it wasn't cheap, none of this really is i guess. lots of people use pressure treated, i'm sure it'll be good for a long time. hopefully you've already bought it and are letting it dry. aim a fan at it for quickest results. you will want to do something to keep it from bowing too...i hate pt wood.

i tried to keep the cap on mine, maybe you'll have better luck. one area of particular concern is right in front of the front partition in the bilge...where the 4 vent hoses enter the bilge area. i'm hoping yours was miraculously designed better than the '87. the factory ran those 4 vent hoses down through the foam in the deepest part of the hull. i think the hoses broke down over the years letting any water that gets in the vents get into the foam with no way to drain out. take a look, the foam from this 2 sq ft area weighed about 40 lbs. the ice chest sits over this area...there was no drainage for the ice chest either.

http://i8.photobucket.com/albums/a10/salty87/IMG_0291.jpg

on the left side of this pic you can see a cut i made before pulling the cap. i took off a bunch of the floor to take a look at the stringers. anyway, that's where the wall/wet bar is behind the passenger seat, as a reference point. the strip of wood on the starboard side is where the dash area was.

[bsampson]

I've ordered everything I need, but didn't get any cabosil/thickener for the poly resin. Local shops don't carry it. I've noticed talc can be used. Can I go to the store and just get talcum powder to mix with the resin to thicken it?

[riveredge]

never tried that... but any online marine supply place should have cab-o-sil or some similar filler... you could always get a little talc, mix some up, and see what happens!

[bsampson]

Or, instead of mixing talc with resin, could I use automotive fiberglass body filler?

[Salty87]

i have not tried it but have read that baking flour works. even cabosil is just a thickener, look it up.

[bsampson]

I just wanted to let you know I looked at the ingredients of automotive Bondo fiberglass filler: polyester resin and talc.

So, I ended up bedding the stringers in bondo.

[wotan2525]

I learn something new everyday.... my boat (since i've owned it) has never had anything in between the windshield. No cooler. No ski locker. Just a floor. It would have been nice if I had replaced it with a ballast tank while my floor was out, but I didn't even think of it.

Welcome to the club BSampson.... hopefully this club is one that nobody else will have to join, because these 80s Supras are a PITA to work on!!

[Ironcross25]

well I think I am joining that club. I have an 86 marauder and my strings will need redone. I had a few soft spots in the floor and then started digging around and the strings are bad too. I hate it right now but what can you do. The question is should I try and do it or have it done for $4400 bucks?

[wotan2525]

well I think I am joining that club. I have an 86 marauder and my strings will need redone. I had a few soft spots in the floor and then started digging around and the strings are bad too. I hate it right now but what can you do. The question is should I try and do it or have it done for $4400 bucks?

If you have the space and the tools (including patience) to do it yourself, I would. There will however, be many... many... times during that process that you wish you had just written a check for it.

When I bought my boat the floor was totally solid. I mistook this for the stringers being solid. Some jackass had replaced the floor to cover up the rot.... as soon as I pulled the floor out I discovered exactly how duped I had been.

[bsampson]

I'm with wotan. If you have the resources and are handy, go for it. I was lucky and my engine mounts were already replaced, so I didn't have to mess with pulling the engine and getting it back into alignment.

I'll probably spend about $1000 in materials to do it myself. I've spent a lot more time than expected though, and I still have a lot to do.

[Salty87]

$4400 can go a really long way. the project isn't rocket science, it's messier than hell and does take a while. i'd mull over it until the end of the summer. study up in the meantime and enjoy the summer.

[Ironcross25]

thanks guys. I will kick it around. I have a 3 car garage so i have the room. I do have the tools but i have a toy in each bay. How hard is it to pull the top? Do you just drill the rivets out then re rivet it when the top goes back on? Thanks

nick