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Spray Coaming Reinforcement and Reattachment

Woodwind

Member
Reinforcing and repairing the deck and reattaching the coaming:

I’ve opted to use West System epoxy with the 407 filler and either fiberglass tape or cloth..
The 407 filler is much easier to sand than the other harder structural fillers and since I’ll be using fiberglass cloth in addition it will be just fine.

Of note is that I am using the Standard hardner. But if you are picky and you want your layup to be more translucent, you can always use the West special Hardner that will give you a clear resin. Standard hardener always quickly turns to a reddish color after opened due to absorbing moisture which gives a reddish colored resin. I don’t think it really matters as the coaming and sealant will cover the entire area that’s been repaired and reinforced. This boat at the coaming had a lot of crazing, chunks of gelcoat chipped out down to the fiberglass, crazing around most of the rivet holes. I got the boat without the spray coming on it. Most of the rivet holes Were enlarged with the rivets not holding the coaming down.
A few of the holes in the coming are enlarged too but I think the rivet heads are large enough to handle this.

The How Part:

Taped off and sanded with 80 grit
Applied one layer of unthickened epoxy saturating all the chipped and crazed areas and oversized rivet holes
Filled all the rivet holes and chipped areas with 407 mixed to peanut butter consistency with piece of small squeegee ( a cut piece of credit card works good too) right on top of the unthickened resin before it fully kicked off.
Don’t worry if the 407 putty gets a little squirrely most of it gets sanded off anyway. Just keep it in between the lines...

If you want you can stick painters tape on the underside of the rivet holes to keep the putty from sagging through into the boat.
I chose to wipe with acetone and then rough up with 80 grit, wipe with acetone again and epoxy half dollar size pieces of mat on the underside at the rivet holes. Kinda punch it in with a chip brush.
You Can’t reach them all due to the foam blocks but you can get to most of them.

When you’ve quit fussing with the epoxy and you can tell it’s beginning to kick, and before it gets hard, pull the tape off so it doesn’t get glued to the deck. After it cures, remask before you sand. No worries, this is an easy area to mask

A piece of one by one makes a perfect with sanding tool.
I rounded the edges a little to keep from gouging.
Wrap a piece of PSA 120 grit around it.
I use Mirka paper, it is sharp and will cut through the 407 quickly and give you a fair surface on which to put your fiberglass.
Sand until fair so you can put on the cloth/ tape next.
 

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L&VW

Well-Known Member
Any "before" pictures? Nice work.

Since the coaming (splash guard) is convex underneath, most of my recent repairs were substantial--but hidden. Holes in the deck underneath--and obstructed from repair by flotation blocks :confused: were the size of a nickle! :(
 

Woodwind

Member
Yeah, LV&W you are right.
I’m going to do a very light lay up on the top.
Starting on it soon I’m not sure if I’m going to do circles or glass tape the entire length.
Taping entire length would give me an even/level and stronger coaming install on the top I think....

Think I forgot to photograph it before I started but I’ll look at my pictures and see if any captured that area.
 

L&VW

Well-Known Member
Any "before" pictures? Nice work. Since the coaming (splash guard) is convex underneath, most of my recent repairs were substantial--but hidden. Holes in the deck underneath--and obstructed from repair by flotation blocks :confused: were the size of a nickle! :(
Oopsy... :oops: Since the coaming (splash guard) is convex concave underneath,
 

Woodwind

Member
Concave!!! Concavity!!!!

PROGRESS!!!

Spray Coaming repair today using fiberglass tape To finish the layup on deck:

Placed the glass tape just shy of the masking tape.
Poured on the resin and squeegeed out the resin to evenly saturate the cloth.
Used a small metal glass roller to level the glass and push the resin into the cloth.

Etched a line lightly into the gelcoat around the perimeter of the layup for stress relief to hopefully stop any rivets from radiating stress cracks Using a razor blade.
Cut off the extra cloth when etching With the razor blade.

A couple spots resin rich but it turned out good.
I marked the rivet locations with a black sharpie before applying the tape, so they could be seen through the layup as a guide for redrilling.

Will let it cure up a day or two and then reinstall the coaming with 3M 4200 in case it needs to come off again.
Have closed bottom rivets with a little bit longer grip wI’ll add aluminum washers under the deck where I can reach them.

Will figure out mounting the main street block next.
 

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L&VW

Well-Known Member
Poured on the resin and squeegeed out the resin to evenly saturate the cloth.
Used a small metal glass roller to level the glass and push the resin into the cloth.

Etched a line lightly into the gelcoat around the perimeter of the layup for stress relief to hopefully stop any rivets from radiating stress cracks Using a razor blade.
Cut off the extra cloth when etching With the razor blade.

A couple spots resin rich but it turned out good.
I marked the rivet locations with a black sharpie before applying the tape, so they could be seen through the layup as a guide for redrilling.

Will let it cure up a day or two and then reinstall the coaming with 3M 4200 in case it needs to come off again.
Have closed bottom rivets with a little bit longer grip wI’ll add aluminum washers under the deck where I can reach them.

Will figure out mounting the main street block next.
Some $20 fiberglass repair kits provide only a couple of "flux-brushes".

While applying resin to the fiberglass, white spots will appear. Those need to be filled with resin, as there's no strength there. The flux-brush bristles are stiff, so, using slow-set epoxy, take the time to "stab" these voids into submission.

While it's not as good as a roller, you use the brush you bought! :cool:
 

signal charlie

Well-Known Member
Staff member
Nice work. I like the idea of using a strip of fiberglass, in the past I have put little squares over holes and redrilled, that was time consuming.

As for filling in cloth with resin, lately we have been using thickened epoxy out of the caulk cartridge, either TotalBoat THIXO or Pettit Flexpoxy. No need to mix filler and the thickened epoxy stays put, and also fills voids like the old river hole. We put thixo on both sides of the cloth. If anyone goes the THIXO route, invest in a High Thrust 18:1 caulk gun vs the basic gun. The unused epoxy stores for quite a while, we leave the old mixing tip on and just put on a new tip when it's time to dispense more epoxy.
 

Woodwind

Member
Thanks!!! :D

Yes, that does sounds easier.
I haven’t shifted to the premixed tubes.... Yet ....... but it interests me.
Does the cloth wet out thoroughly?

Sounds like you can buy extra tips and it doesn’t separate in the tube or harden in the tube.

One day....

I figured if I ever built a stitch and glue or one of those beautiful Chesapeake Light Craft kits I would start using Thixo for the fillets.

when I run out of my West System stuff ha ha ha :eek:

I did use a 2 inch chip brush when I poured on the resin initially to work it in As I was out of what I call the “acid brushes” I think they’re the same animal.
Harbor Freight item, reasonably priced, they mail Order too.

A squeegee or a cut credit card are very handy to squeegee out the excess resin After you’ve worked the resin in.
A good use for all your old credit cards.
 
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Breeze Bender

Breeze Bender
Yep, I had the stainless screws with rivnuts. Can’t access behind most of the screws, even with a port, because of interior blocks. I filled the holes with Thixo and redrilled, then used rivets (after painting the deck and coaming). Your materials and method sound great.
 

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Woodwind

Member
Nice work!!! Nice paint job! :cool:
Great Pics, they always help!

I see a roll of butyl tape did you use it to seal the heads of the rivets?

I think I’m going to use 4200 for my sealant/adhesive, I have a partial tube hanging out.

Yep, I think I will have been able to build a boat out of blue 3M tape by the time I finish this Sunfish project. :rolleyes:
 
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