3.0L to 4.3L mtr mounts and 25 yo transom

[alldodge]

Have my jigsaw puzzle replacement piece PB'd together and curing

Did you use CSM between the two layers of plywood right for ester resin, or biax between for epoxy?

 

[Rick Stephens]

I

Did you use CSM between the two layers of plywood right for ester resin, or biax between for epoxy?

built it with chopped strand.

 

[alldodge]

OK, your using epoxy right?
I just don't use PB between layers of ply wood, only against hull. If I do another thinking about splurging and using core bond

 

[Rick Stephens]

I copied the original for the most part. Original transom had CSM between - they did it strange and left some hanging below which bonded to the hull. So had this 'T' shaped glass sticking up at the bottom when I removed the wood. Not sure how they kept the glass from saturating when they laminated the transom pieces.... No matter, it cut out easy enough.

For a little ol' V6 I think a couple layers of 3/4 ply with epoxy and CSM laminating them, and some 1708 over the top tying into the rest of the transom and the stringers will go the job. Is it ok just to use canned insulating foam to replace the foam I chopped out under the floor? I have a couple cans sitting around from a stock water trough project last year.

 

[alldodge]

Don't see much issue with a small amount of can foam. My guess is all the foam in it is open cell, just like mine was. So far as your build I like it, should be plenty strong.

 

[Rick Stephens]

What amazed me, the foam was dry. And yeah, it was open cell. Light as a feather. I was expecting a mess on the starboard side.

 

[JASinIL2006]

Sounds like you're building it strong! Maybe you should pop a V8 in there to take advantage of that strong transom! :behindsofa:


If the foam-in-a-can is closed cell, I'd go ahead and use it below decks. if it's open cell - and I thought I read somewhere that most of it is open cell - I'd be hesitant to put it anywhere it might be exposed to water. Why do all this work and then put something absorbent below deck? If any moisture did find it's way down there, open cell foam would make sure it didn't leave. Doesn't make much sense to me.

 

[Rick Stephens]

If the foam-in-a-can is closed cell, I'd go ahead and use it below decks. if it's open cell - and I thought I read somewhere that most of it is open cell - I'd be hesitant to put it anywhere it might be exposed to water. Why do all this work and then put something absorbent below deck? If any moisture did find it's way down there, open cell foam would make sure it didn't leave. Doesn't make much sense to me.

The foam that is in the boat is open cell. The foam in can I have no idea, I'll read the can tho and let ya know. I pulled a hunk of original foam out of the starboard side about size of a quart bottle, right next to the drain. And there is about an inch between the foam and the deck right at the stern. I figured I could fill the gap, fill the little cut out area and trim to fit the replacement patches.

Still amazed the original foam had literally zero water in it.

 

[Woodonglass]

Again, the original transom prolly was built with Polyester resin and thus the use of CSM. Since you're using Epoxy there is really no reason for the CSM. It adds little benefit to the lamination since it has very little structural strength due to it's loose fiber construction. It's manufactured mainly as a binder for Polyester resin so the Styrene in the resin can break down the fibers and use them to keep the resin from breaking apart once fully cured.

The "Great Stuff" foam in a can IS closed cell but...still not very GOOD STUFF!!! If it's a very minimal space then I suppose it might be OK to use it as long as the outer skin is never compromised it will remain fairly "Water Proof". Compared to the Marine Foam it is very expensive.

 

[Rick Stephens]

Thanks WOG. I'll have to do some reading. Never thought about it before. Looks like Evercoat makes a closed foam in a can. Small a space as I have to do would be good to be in a spray form. http://www.iboats.com/Sealant-Spray...733307--session_id.698943704--view_id.1183105

 

[Rick Stephens]

Sounds like you're building it strong! Maybe you should pop a V8 in there to take advantage of that strong transom! :behindsofa:

Who needs a V8??

https://vimeo.com/5716555

 

[Rick Stephens]

Again, the original transom prolly was built with Polyester resin and thus the use of CSM. Since you're using Epoxy there is really no reason for the CSM. It adds little benefit to the lamination since it has very little structural strength due to it's loose fiber construction. It's manufactured mainly as a binder for Polyester resin so the Styrene in the resin can break down the fibers and use them to keep the resin from breaking apart once fully cured.

Woodonglass, thanks for the details. I wanted to elaborate on the reason for the chopped strand between my ply lams. My thinking wasn't that it would be stronger, main thought was that having a light weight layer in there would set my resin thickness when I squeezed the lams together. Side to side and top to bottom having that bit of glass would maintain a constant. I got both sides soaked, then when pressed together had plenty of time to pull it down and get it even. In the end the plywood will be sealed inside glass layers completely, the inner glass won't really mean a thing.

Rick

 

[JASinIL2006]

Who needs a V8??

https://vimeo.com/5716555

Couldn't hurt!

 

[alldodge]

Bet that 1000 hp V6 makes the 1K in the 8 to 10K rom range. Would need to find 5 degree pitch prop or a 5.0 drive

 

[Rick Stephens]

No Title

Spent a little bit this evening cutting down my lams to fit. Mounts are trimmed about as small as I think I can make them. 2 piece mounts, 4 inch high and 1 1/2 inside the existing stringers. Still need to sand and better fit the transom patch, then mark and cut the keyhole out.

 

[Rick Stephens]

Got the new transom in, tabbed into place with a layer of 8 oz, and the motor mount bases PB'd in.

Still have a 1708 layer to go over the entire transom. The upper halves of the mounts and all the tabbing and glass build up on them. undefined

 

[alldodge]

Looks real good, You probably know, but just in case, final thickness should be between 2 and 2 1/4 inch

 

[Rick Stephens]

Looks real good, You probably know, but just in case, final thickness should be between 2 and 2 1/4 inch

Thanks. WIll take some glass to get there. Original transom had a 1/4 inch ply stapled over the keyhole to give it just barely, well, almost enough, it was right at inch and seven eighths. I'm starting out at inch and three quarters. Already stuck a layer of 7.5 oz cloth over the center, over that a layer of 1708 will cover the entire transom. Then whatever it needs, it gets in the center. Should be close already.

Today the 1708 and the other half of the mounts. Waiting on closed cell canned foam to arrive to do the holes I cut in the floor.

RIck

 

[alldodge]

Here is the install manual if you need it. Newer version but info is still good
http://www.boatfix.com/merc/install/gas/86017211.pdf

 

[Rick Stephens]

Got the mounts in and a layer of 1708 over top of the transom. Added a couple 16 inch wide layers of 1708 in the middle of the transom to build it out to 2 inch. Now I have to finish the transom and install the transom plate to make sure my motor mounts are level and the right height. No use doing that twice. I like Mercruiser's crossed strings method of leveling. Thanks for the manual AD, easy instructions that keep one from forgetting something.







Mounts are not quite level. I'm going to grind off 3/16" off the port side before glassing it - that is if the rough level I was able to do checks out measuring off the transom plate as well.