Adding stringers to reinforce mast step and trunk.

[Canracer]

I plan to build the type of frames that are visible in this int.505 (mine will be under the cockpit.) Can anyone tell me, what is this style of frame and how can I learn to install them correctly?

 

[Canracer]

The cap and the overall shape look easy enough, but I'm not clear how the bottom edge is attached to the int.505 hull. It looks like it makes contact with only the stringers.

I have templates for the tanks and for the area alongside the trunk.

 

[Canracer]

Here's a diagram of the planned bulkhead locations. I don't want them to print through to the outside of the hull, but I'm not sure right now how that's done.

 

[Canracer]

I towed the boat to the launch on Sunday (to locate the leak) and the truck overheated. That project will have to wait a few days.

 

[Canracer]

I decided to put the epoxy away for now; I'm trying out this polyester.


This was the original state of the stringers. God only knows what the factory was thinking when they built this. Shouldn't this be attached to the hull?


Now it's attached. I cut away the old globs of "fiberglass" and laminated in 3 x 8" wide strips of mat, and 2 x 8" wide strips of roving. The outboard sides will get glass also. I wish it looked neater, but access is extremely limited.


Western Red Cedar planks for the stringers.

 

[Canracer]

Before: Lots of trouble.


After: Everything was cut away and most of the old brittle fiberglass was removed. It's been a dusty couple days.


The same camera position, looking forward. That compression post is currently on schedule for replacement. (See the dust?)


Here are the new stringers. The tapered ends should be easy to drape with cloth. They are 1" by 3/4". One set is 5' long and the other set is 4' long.

 

[Canracer]

I'm bedding the stringers in this biax. and then covering with that tape.

 

[Canracer]

The stringers are in place. That cured squeeze out cleaned up easily (surprising) with a Dremel and a small barrel sanding bit.

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[Canracer]

Cleaned up the resin spills, fillets added, and the cedar was covered with 4" tape. I was also able to finish trimming those limber holes.

 

[Canracer]

I have still tacky polyester (no wax) and I want to cover that with epoxy. Is it OK to apply epoxy on top of the slightly uncured layer of polyester?

 

[Canracer]

I'm guessing it will form a chemical bond?

 

[Jim Caldwell]

Most epoxy instructions say it will stick to fully cured poly only.
Check yours.

 

[abourgault]

In order to your no-wax polyester to cure just spray some PVA over it. The PVA will create an air barrier and the resin will cure. You will need to wash that PVA before applying the epoxy.

 

[Canracer]

You guys are right. I just got off the phone with a tech. at West System, and at FGCI.

Both companies put me right onto the line with a technician who was willing to listen to all my questions. So that was cool.

The consensus was that I shouldn't apply epoxy on top of tacky polyester. I get the impression that it's not exactly known if the bond will be strong, but rather that I should follow the current "rule of thumb."

 

[AndySGray]

I can't fully tell from the photo, but looking at the one above where you say



'Western Red Cedar planks for the stringers'


The matting looks like it hasn't been worked enough, a few patches of the matting look a little dry but as there is plenty of goop on the edge I suspect it might have benefitted from a little more stipling or rollering (however you did it).

If you look at a single strand of glass closely, rub it between your fingers and you'll find it's actually made up of hundreds of much smaller fibers. If you can work the resin into and between these fibers it will become transparent and also result in a much stronger finished item.

Don't worry about the one you've done there - you've beaten the factory quality and how long had that lasted .

The fillets look great - I only mentioned the one above as I find it's common for people to apply more resin so that it can soak in, when they can get away with less by working it deeper into the strands more effectively - this gets to be a useful technique when you're working upside down and you don't want the excess running everywhere. The racing guys often talk about the perfect ratio of resin to glass when a few extra pounds of resin make it heavier without adding strength...

I am not trying to be critical, it is offered as a suggestion that I hope you can use. Think you're doing a great job and you'll have a fantastic boat when you're done;- the itching goes away after a few days (usually about the time you discover the next bit that needs to be ground out/sanded, dammit)