1974 20' sceptre transom replacement and i/o to outboard bracket conversion

[flyingfrizzle]

Originally Posted by strick

I know pictures can be deceiving but how wide is the area you ground down in the photos? It appears only an inch or two at most? If so you may run the risk of it cracking down the road due to insufficient glass holding the two parts together. Better to go 4-6 inches...just saying

strick

Thanks for the info, I better make the joint wider. I would hate to have it crack. It is hard to tell in the Pics but the areas I glassed are mainly 1" on each side. I ground them down so that there was a 1/4" gap between them so that the matt on the back side would bond to the glass and matt on the front. The edges of the pieces are ground so that they are tapered to sharp edge and when filled they don't have any air between them. I used two layers of 17oz matt 4" wide on the back side then a 1708 strip over that. Most of the beef is on the back side. Oh yea it was hell getting it on the back side. I had resin all the way to my elbow. I was hoping that all the strength would come from where the back side had the wider, thicker, glass and since it is bonded threw the center gap and filled solid. Now that you guys say this I will go back and grind out a 6" wide area over the seem and lay another 2 layers of matt on the front to help bond it together better. I'm learning still every day so thanks again for the help. I will try to fix what has been done an then move forward with that in mind as I go.

[flyingfrizzle]

Here is a Picture on how I originally filled the gap an then added the layers on the back side. I plan on grinding back the surface more down an 1/8" or so 6" wide on the front side then adding two layers of matt. Then I will fair it back in again.

[parrott]

Yeah alittle wider is a good thing. Biggest thing is romove the gelcoat from the glass.
Maybe even try putting some 1.5oz matt over top of the 1708 for your final layer. Gives you something to sand so you are not sanding the threads of the 1708.

[Blue_Heron]

I think the rule of thumb is a 1:12 taper when you grind it back. So if the laminate you're splicing is 1/4" thick, you would grind it back 12/4" i.e. 3" on each side.

[beastley]

I just reinstalled my caps that where cut roughly the same as yours. Found a neat trick for glassing the inside face. Wet out the strips on a piece of wax paper, the pull the strips off and apply. Obviously use gloves, but it was much easier then trying to wet out the glass upside down laying on your back.

[gofastsandman]

Originally Posted by beastley

I just reinstalled my caps that where cut roughly the same as yours. Found a neat trick for glassing the inside face. Wet out the strips on a piece of wax paper, the pull the strips off and apply. Obviously use gloves, but it was much easier then trying to wet out the glass upside down laying on your back.

That`s the kind of tip that makes this place home.

Cling film or visqueeene and Poutine sauce works as well.

[flyingfrizzle]

Blue,parrott,strick,gfs- Thanks for all the good information, I will put it into service as I carry on. Got 5 more to do after this one! The more I can learn the better. So much knowledge up here on this site. Thanks guys!

beastley- That is how I applied the strips on the back side. That is about the only way I could do it. Used a roller with some west 4" rollers inserts and rolled the resin on the fiber before I placed it behind the back side. Still even with gloves got resin from my wrist to my elbow. Fun stuff!

[Bushwacker]

Originally Posted by flyingfrizzle

. . . Still even with gloves got resin from my wrist to my elbow. Fun stuff!

Good thing you're not using epoxy! Some folks become very sensitive to it!

I have a neighbor in the yacht building business that grew up on "Thunderboat Row" in Miami in the 60's, and he is so allergic to epoxy that he can't get anywhere near it! He said the problem is the nasty chemicals in the catalyst, and cautioned me to ALWAYS use a carbon filter respirator when working with it even though it has very little odor, and to be very careful to keep it off the skin. Even though poly/vinylester smells a lot more, he said it's not nearly toxic as epoxy!

BTW, I notice you're using a lot of mat. It's good for building thickness and the random fiber orientation helps carry off-axis stresses, which is why it's used between layers of woven cloth or roving, but the fibers are very short, so that stuff has very little strength. Even light weight cloth is MUCH stronger because of the long continuous fibers!

[parrott]

Anytime man. Yeah I wet my 1708 out on a piece of plywood. Course w mat side up. Cant do huge piece. Brush some resin where u are sticking cloth too.

[flyingfrizzle]

Went back and ground down the seems around the rear cap about 3"-4" each side and will add a piece of 1708 then a layer of matt over that and them fair back in. Hopefully this will make it much stronger. Thanks to all who helped with the seem grind back info...

Here is part of it that was ground back ready for the wider cloth. You can see the 2" wide area in white where I seemed it together the first time and where I ground it down to make the next layer much wider: