1990 Rinker 236 sport cuddy restore-Stringers and motor mounts

[Woodonglass]

Getting Bulk with 1708 is a bit problematic. That's one of the Good things about Woven Roving. It Does build strength and Bulk in a hurry. On the other hand the good thing about 1708 is...you don't NEED the bulk to get the same amount of strength. One layer of 1708 is stronger than a layer of CSM and 24oz woven roving which is twice as thick. So unless you just absolutely need/want the thickness, I'd put down two layers of 1708 or maybe 3 and be done with it. Now to directly answer your question, you'd prolly have to lay down 8 layers of 1708 to get 1/4 inch of glass.

 

[GracieBell1]

Holy hounds of hell Batman! 8 layers is crazy and I guess I did not realize 1708 was that much stronger. This is for the motor mounts and engine stringer. The glass going over the top was about 1/4 thick. May just use 3 layers of 1708 and 2 on the stringers.

 

[alldodge]

Really 8 layers of 1708 for 1/4 inch, you sure about that?

 

[GracieBell1]

No Title

So I am still not sure which way to go. When my engine mount and stringer were put in from the factory they hs only glassone side of the strnger. In the pictures you will notice that when Rinker glass the ONE side they layed a piece of ply flat on the hull then glassed over the frlat ply and up the stringer. Then Rinker put a block of plywood strips on top of the flat ply that was glassed to the hull with the stringer.This plywood block was siting on top of the flyat ply on the hull. Rinker then glassed over the wood mount over top of the stringer and across plywood decking that sits on top of the stringer and over to a cleat on the next stringer. My question is, should I glass the stringer in then put downt he flat plywood for the base of the mount or should I do it the way Rinker did from the factor? also, I am definetly glassing the back side of the stringer. also If you notice from the first pic that there is a "tail" of oplywood behind the mount. For the life of me I cannot see why Rinker mad the mounts with this extended piece of plywood at the bakc of the mounts. I plan on not exteding the plywood bpast the mount base.

 

[GracieBell1]

You can notice the extended flat plywood piece at right side of the mount in pic 3.

 

[alldodge]

From the looks of it you have not yet removed enough of the tabbing and stringer. I would cut it right along the orange line which includes removing the end piece down to the hull.



The wood to the right also doesn't look good. Is it dry?

So far as how to box or glass it in, I suggest figuring out how the water got in. Once you know this and can stop it, there won't be a next time.

 

[GracieBell1]

Well I realize that I have not removed everything! All of the wood is bad. That was not my question. Also, 5he water intrusion is irrelevant to how I am going to lay up the new motor mount, as this was my question.

 

[GracieBell1]

I may not have been clear before. But I am really just contemplating tabbing in the stringer then building the mount and glassing over it. As apposed to the way Rinker did it. Which was to tab in the stringer and flat board together then built the rest of the mpunt on top of the tabbed in flat plywood and stringer. Hope this makes sense

 

[alldodge]

Well I realize that I have not removed everything! All of the wood is bad. That was not my question. Also, 5he water intrusion is irrelevant to how I am going to lay up the new motor mount, as this was my question.

Sorry to have misunderstood, this makes twice for me on this thread, I'm out I'll leave it to others

 

[GracieBell1]

oh your good. not problem at all. Just not sure if I should go with the factory design. It just seems that glassing over the flat plywood and stringer give less of a bonding area for the glass to the hull.

 

[Woodonglass]

Really 8 layers of 1708 for 1/4 inch, you sure about that?

Well you can take a look at this, and make your own calculations...I was referencing the 18oz woven Roving and using the Thickness per Ply column. .029 per lamination. 1/4" is .250 soooooo....8x.029=.232 so that's where I got 8 layers. But...I AM just an Old Dumb Okie soooo you Might want to check my Math!!!!!

 

[GracieBell1]

biax 1708 is .044" thick. I may be reading the chart incorrectly but is biax is .044" then it would be thicker than 18oz woven roving

 

[Woodonglass]

Good Catch, I TOLD you to check!!!! Sooo based on that it would take about 5-6 layers of 1708 to yield 1/4" of Glass. Hey, I keep telling ya...I'm and Old Dumb Okie!!!! If you're using epoxy then it would take 8 since there's no CSM stitched to the fabric which increases the bulk.

 

[GracieBell1]

A layup for woven roving that would be 5/16" thick is mat, roving, mat, roving, may, roving, mat mat. I am wondering if I put down 3 layers of 1708 would that would be equal t9 or stronger than the 1/4" that is is now.

 

[GracieBell1]

I assume the layups would go faster with 1708 as opposed to may and roving.

 

[Woodonglass]

Uhmmm Not necessarily. You can do them wet on wet sooooo...as soon as on layer is down the next can be applied. One issue is Heat. with Poly resin, the Thicker the lamination becomes and the more resin applied the exothermic heat of the chemical reaction starts to take effect and the heat can become quit intense. You have to be careful with it. You could prolly do 3 layers or 1708 at one time with no issues.

 

[GracieBell1]

I spoke with Steve at US COmposites and he also said about 5-6 layers to get 1/4 thick. He suggested 4 layers. I may bail on the 1708 and just use mat and woven. I am worried that if I use 1708 I will not get the strength I need without using a bunch of layers.

 

[GracieBell1]

I was incorrect before in saying that Rinker put the stringers and bulkhead directly on the hull. I was wrong they floated them about 1/8" off the hull. My question is should I float the stringers and bulkhead or bed them in pl premium. I would rather us pl but the bulkhead has so many turns that it may not all rest on the hull if I use pl premium. I would then have to fill any gaps that may exist after bedding it in pl. I may just float it all and use some strips on csm to hold it in place until I tab it in.

 

[Woodonglass]

I wouldn't use PL

 

[GracieBell1]

So I was thinking that maybe Rinker made the base of the motor mount so long to be equal to the length of the stringer. Since the flat ply base does not creat a hard spot Rinker was able to put the stringer right next to it against the hull. The motor mount stringers did not seem to be floating like the rest of the stringers and bulkhead.