Best way to modify fiberglass?

[TooCoys]

Originally Posted by minaret

How about some pics?

I'm getting started on it tomorrow morning. I'll post pics as I go along.

[TooCoys]

After watching umpteen youtube videos about fiber glass, including an entire fiberglass series by boatworks today, I think this is the approach I'm going to take.

I'll trace out a piece of 3/4 birch ply to fit the existing opening. Then I'll put the new hatch on it and trace the cutout. I'll cut the hole for the hatch and create a "ring"spacer. That will be secured to the existing deck with screws and 5200. I'll place the ring slighting below the deck leaving place for the fiberglass. Once the fiber glass is cured on top, and down the inside of the cutout, I'll use bondo to fill in the low spots. Once that sets up, I'll come back with white gel coat. I'll sand everything down with 220 or 400 grit so that the modification is flush with the existing deck.

And then after all that, I'll install the new hatch. I've created another crude diagram from my mental picture, and I am thinking it will look something like this.

[TooCoys]

hmmmm.... After watching more videos, now I'm thinking that the white Marine Tex may be the way to go to seal the gap between the deck and the shim.

[UNCIVILIZED]

Originally Posted by TooCoys

hmmmm.... After watching more videos, now I'm thinking that the white Marine Tex may be the way to go to seal the gap between the deck and the shim.

Mixing up a DIY bedding/base casting epoxy bog generally works quite well, even as compared to Marine Tex, as you can custom blend it to optimize whatever properties are called for by the job. Such as being non-sagging, structurally superior, quick or slow setting, etc. Depending on what, & how much of many of the various ingredients that you use to mix it up.

My stating the above about MarineTex isn't because I don't like the stuff, but rather that it's a lot more difficult to bed something large such as a hatch, when using a stiff, thick putty such as MarineTex. Where as a custom blended bog (thickened epoxy) can be purpose tailored for such jobs. Including mixing it so that just the weight of the hatch alone, is enough to perfectly level out the thickened epoxy mixture, thus giving you an ideal, custom molded platform on which to bolt a hatch. Or to use such a mix to bond to pieces like a deck, & a hatch spacer together.

Which, 99% of this stuff, & much much more is covered in the WEST System user guides, & free downloadable books at their website. Including the classic The Geugeon Brothers, On Boat Construction. Plus there are lots & lots of projects done by users of their products, explained in detail at said site, & the sister site www.Epoxyworks.com

Plus they, & System Three Resins, etc. have customer support lines that you can call with questions. And there are other sites which cover tons of stuff on boatbuilding & repair, such as www.BoatDesign.net/forums for example. And any epoxy/composites vendor will have similar help sections on their websites, including videos. Plus you can learn all kinds of skill & info from places like www.CompositesWorld.com & www.Proboat.com (Professional Boatbuilder magazine).

[Three Sisters]

Hi.

It appears from the diagram that you will be screwing the plywood ring spacer through the plys of the plywood horizontally. This may work if only snugging up the screws via pre-drilled holes. Any further tightening i can see the plies seperating and thus destroying the ring spacer. Am I looking at this right ?

[TooCoys]

Originally Posted by Three Sisters

Hi.

It appears from the diagram that you will be screwing the plywood ring spacer through the plys of the plywood horizontally. This may work if only snugging up the screws via pre-drilled holes. Any further tightening i can see the plies seperating and thus destroying the ring spacer. Am I looking at this right ?

Yes you are. I was going to drill horizontal pilot holes for the screws, and counter sink them a bit.

I just finished a 12 hour shift, but I'm going to have a bit of coffee and head to Home Depot for wood and all the fixins.

[TooCoys]

Originally Posted by UNCIVILIZED

Mixing up a DIY bedding/base casting epoxy bog generally works quite well, even as compared to Marine Tex, as you can custom blend it to optimize whatever properties are called for by the job. Such as being non-sagging, structurally superior, quick or slow setting, etc. Depending on what, & how much of many of the various ingredients that you use to mix it.

My only fee with mixing the peanut butter as the boatworks today guy does, is that I won't be able to get it smooth an even. Additionally, I'll have to put gel coat on it to make it flush with the existing deck.

I don't know what I'll do. I'll take it a step at a time and see what I'm working with. I'll post pics once I get to that stage.

[jimbunyard]

If all you're making is a trim ring to dress up the interior of the boat around the new hatch,



this will work fine.

However, if the flange that secures the hatch to the boat is fastened to the 'trim ring' as the primary method of holding it to the boat, the joint between red 'glass layer' and 'existing deck' (as drawn, at any rate) will likely fail, probably in reasonably short order...

if the flange of the new hatch is bolted or screwed into the 'existing deck', with proper bedding you'll be good to go.


Is the deck core plywood or balsa?

The size 65 hatch wouldn't work?

[minaret]

Originally Posted by TooCoys

After watching umpteen youtube videos about fiber glass, including an entire fiberglass series by boatworks today, I think this is the approach I'm going to take.

I'll trace out a piece of 3/4 birch ply to fit the existing opening. Then I'll put the new hatch on it and trace the cutout. I'll cut the hole for the hatch and create a "ring"spacer. That will be secured to the existing deck with screws and 5200. I'll place the ring slighting below the deck leaving place for the fiberglass. Once the fiber glass is cured on top, and down the inside of the cutout, I'll use bondo to fill in the low spots. Once that sets up, I'll come back with white gel coat. I'll sand everything down with 220 or 400 grit so that the modification is flush with the existing deck.

And then after all that, I'll install the new hatch. I've created another crude diagram from my mental picture, and I am thinking it will look something like this.

Many things wrong with this diagram. If the new glass does not lap onto the old glass, as depicted, there is no point in applying it. In fact, as depicted, no glass at all is needed.

[George DuBose]

Skylark had a hatch over the salon that wasn't "blue water rated - by me anyway" and I wanted to change it for a more robust model.

I liked the Lewmar hatches, but no one made a hatch that would be an exact fit.

So...I cut the raised portion of the hatch aperture flush with the deck and then took a 1/2" piece of HDPE and cut it to cover the original aperture and then cut a smaller "window" to the dimensions of the new Lewmar.

West Systems advised me to "oxidize" the HDPE by heating it slightly with a propane torch and then used West System G/Flex to bond the HDPE to the fiberglass deck.

The hatch was mounted to the HDPE with screws.

So it is possible to alter the size of an aperture to fit a hatch of another dimension. Within reason. I suppose there are limits to the size difference between the new hatch and the old aperture.

[sean9c]

The Bomar hatch has to go on a flat surface, no camber. Has it ben determined that the surface is flat?
Would it be easier to just build a new hatch to fit the existing opening?

[TooCoys]

After removing the old hatch and dry fitting the new one I decided against any major fiberglass project. For the time being I opted to rescue the existing frame. I've built a top frame out of 3/4 ply that will be topped with plexi.

I'm probably just tired from being up over 24 hours straight but right now this hatch has me wishing I had never bought this boat.

[dtrue]

Hi TooCoys,
In my experience, it is easier and somewhat of an improvement in many cases by laminating on core up from deck a couple of inches or broader base even with the needed closure. Allows you to finish inside nicely, only building up needed in the area of previous core, you may even wish to pre-form inside as desired in a few hrs and then apply to inside of closure in 6-8 hrs. Everybody doesn't bid time and cost daily so work habits may differ the time of coarse, as well as all tools in reach. All supplies there. Good Luck Dan t

[Three Sisters]

Originally Posted by TooCoys

After removing the old hatch and dry fitting the new one I decided against any major fiberglass project. For the time being I opted to rescue the existing frame. I've built a top frame out of 3/4 ply that will be topped with plexi.

I'm probably just tired from being up over 24 hours straight but right now this hatch has me wishing I had never bought this boat.

Agreed, that's just the ticket for the time being until the procedure can be think tanked through.

Lots of options.

[TooCoys]

So as I said I opted to NOT do any glass work at this time, especially because I haven't don't it before. Instead I rebuilt the wood frame, and installed some plexi. I mounted the plexi on the wood using 3M VHB tape, and sealed the bottom with butyl tape. Hopefully this gets me through the season.

During the summer I am going to get some scrap wood and get to know fiberglass a little better. Once I'm confident in my technique, I'll take out the existing hatch, put in a new core, and glass in the hole. Once that's done, I'll be able to cut a brand new hole for a new complete hatch in any size or shape I desire. I'll hopefully be able to do this next fall during the off season.

Here is the outcome of my DIY hatch repair.