Need "how to" link for glassing over thru hull holes

[Seattle Scott]

At next haul out I and going to relocate a below waterline thru hull and pull out a couple of transducers ( one I have no idea what it was supposed to sense) and the broken speedo. So I will be filling in 4 holes variing from 1 1/2 inch to 3/4 inch in fiberglass and I am looking for "how to" info.

 

[sailaway78]

Check out Main Sail's website

Check out Main Sail's site. Seems like there was a discussion not long ago about this same subject, and I think Main has some info. posted. If he does, it won't get much better.

 

[Ross]

I can recommend a very good book. Alan Vaitsis

Fiberglass Boat Repair and Building. This is the best of about four that I have and a dozen that I have seen. I can tell you this much you will need a 4 1/2 inch right angle grinder with a sanding kit and a bunch of 25 grit disks and a few 50 grit and 80 grit.

 

[Maine Sail]

I don't actually

have that on my site yet. #1 Bevel back both the inside and outside of the hull in a tapered fashion. This is tough and a I wish someone made a tool specifically for this but they don't. I use a Dremel or angle grinder.#2 Cut circles of fiberglass cloth/roving/mat starting with the smallest to biggest diameter (you are matching the bevel you cut). You will then needed to epoxy these in place on both the inside and outside of the hull re-building the laminate schedule. I would not use polyester resin for this as it has low secondary bonding characteristics and epoxy will be much stronger..When you've built it back up fill and fair it over then cover it with Interlux 2000E barrier coat or epoxy with barrier additive.

 

[Ross]

The bevels need to be about 6-10 times as wide as they are deep

it makes a nice saucer shape inside and outside. The edges of the bevel should meet at a pretty thin edge. Personel safety is a must.

 

[RichH]

Go to "epoxyworks"

http://westsystem.com/webpages/epoxyworks/projectdirectory.htm Index for repair, building, etc. with epoxy fiberglass This project site will give you the optimized 'tapers' that you''ll need to refer to for optimized strength of such a repair. Eg. for a 3/8" thick hull you will need to taper (usually 20:1 ... 3/8 = 0.375; 0.375 X 20 = 7.5") the hole to approx 7.5 inches diameter on the inside and taper that down to the 1.5 or .75 inch hole on the outside so that you wind up with that approx. 20:1 taper on the original material. .

 

[Seattle Scott]

Jeeze, the inside bevel is going to be a bear

with the limited space to get a grinder in there. Guess I will be owning a dremel at some point. The double bevel makes sense so the patch won't pop out and won't pop in.

 

[Maine Sail]

Scott..

Sorry I forgot to mention the bevel ratios as Ross and RichH have. It is possible to do an exterior only bevel but it gets big and IF you can do it from both sides it's a much better & stronger idea.The Dremel "flexible wand" is one of my all time favorite tool accessories..

 

[Ross]

I like to at least scuff it up on the inside and apply

a couple of layers. But when I was doing my keel I was patching 1/4 inch holes for those I just put three or four layer postage stamps on.