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Discussion Starter · #1 ·
My sailboat came equipped with a water depth indicator. There is a 1 inch hole drilled through the hull about 2 feet below the waterline where the transmitter or whatever it is called exited the hull. I have remove all this old equipment and now need to fill in the hole. Question is how do I do it. The thickness of the hull at this point is 3/8 inches thick. Do I try and fiberlass in and over it or plug it with something. Both sides are accessible. Thanks
 

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Discussion Starter · #3 ·
The boat also came with a 178C Garmin which has a depth sounder. The remote unit is glued to the inside of the hull and the old one which was thru the hull was no longer being used.
 

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I had a similar arrangement on my last boat.

You need to fill the hole:

1. Taper the inside and outside of the hole so that it's no longer a 90 degree edge. Sort of like a sink drain.
2. Remove all traces of paint on the inside and outside. Wipe with acetone
3. Obtain fibreglass roving cloth. Cut several pieces the size of the hole
4. Tape over the outside of the hole with masking or duct tape to temporarily seal the hole.
5. Mix up some West Epoxy or equivalent, soak the roving, and insert in the hole. Repeat once more. Tamp gently to remove air bubbles (This is really important). Let stand until hardened
6. Remove the tape from the outside
7. Repeat #5 until desired thickness is achieved. Make sure to remove all air bubbles.
8. Cut and epoxy a larger cloth piece to overlap the edges of the hole by about 1" and apply to the inside of the hole.
9. Mix collodial silca to thicken the epoxy and fair the outside of the hole.
 

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Discussion Starter · #5 ·
Drilled hole in Hull repair

To Saberman: With the thickness of the hull being 3/8 inches do I fill the hole at one time with the epoxy and roving cloth or do I do it in stages and once it is full do I apply a larger piece on the inside as I should do on the outside. Thanks
 

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I would do it in stages. Put in a couple of of layers of cloth, get rid of the air bubbles, let it harden, then a couple more, repeating untill all 3/8" is filled. When all is done, apply the last layer of roving on the inside.

I hesitate to put a layer on the outside because fairing it will be a real pain and you'll probably sand it all away anyway. That's why I suggested using collodial silca as a fairing. You can usea a lower density West fairing compound, but the silca is really strng stuff and this is an important repair.

To put the repair in perspective, it's a small hole and not in a load bearing area, so ther really isn't a need to cover the outside with cloth. After you fill with all the layers of roving (NOT mat) and the final layer inside, the repair will be as strong as the area around it. MAYBE if you pounded a hammer on the exact hole, MAYBE it would give, but I doubt it. There may be some disagreement on this, but I would feel confident with this repair on my boat.

All things considered, this is a simple repair and can be completed in a couple of days (most of the time is spent waiting for the epoxy to cure). A note of caution - don't cheap-out and use fibreglass resin. Use epoxy.
 

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I had a similar arrangement on my last boat.

You need to fill the hole:

1. Taper the inside and outside of the hole so that it's no longer a 90 degree edge. Sort of like a sink drain.
2. Remove all traces of paint on the inside and outside. Wipe with acetone
3. Obtain fibreglass roving cloth. Cut several pieces the size of the hole
4. Tape over the outside of the hole with masking or duct tape to temporarily seal the hole.
5. Mix up some West Epoxy or equivalent, soak the roving, and insert in the hole. Repeat once more. Tamp gently to remove air bubbles (This is really important). Let stand until hardened
6. Remove the tape from the outside
7. Repeat #5 until desired thickness is achieved. Make sure to remove all air bubbles.
8. Cut and epoxy a larger cloth piece to overlap the edges of the hole by about 1" and apply to the inside of the hole.
9. Mix collodial silca to thicken the epoxy and fair the outside of the hole.
Following this repair method will result in a very week spot in your hull that could pop out under severe weather conditions. Don't do it! Do it right or hire it done by a professional! Doing it right involves grinding the hole back at a 12 to 1 ratio. That means that for your 3/8 inch thick hull the outer edges of your ground out area will be 4.5 inches away. Then gradually build up with larger and larger pieces of fiberglass roving until the final piece is the full 10 inches diameter. Actually Ferenc Mate says in his book "Shipshape, The Art of Sailboat Maintenance" that if the hull is greater than 1/4 inch thick then the ground out ratio should be 15 to 1 but everyone else that I've read recommend only a 12 to 1 ratio.

The rest of Sabreman's recommendations are quite good. That is cleaning the area very well, etc.
 

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One option to consider is to leave the transducer in place. It is a solid plug and has no moving parts. Many feel the depth sounder is the most important instrument, and having a back up ready to go is not a bad idea. A through hull transducer will also be more acurate, although I understand the newer surface mounts are pretty good. It seems different manufactures of displays use the same transducers so you may have options as to how to read the depth.
 

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here are the west systems video's on basicly what and how you want to do it

now you dont need to cut the hole bigger like they, also for a 1 inch hole you wont need the piece backing the hole up. i would use 7 OZ glass not roving, roving is hard to wet out with resin. the big trick i dont think they show on the vid is when you have the glass in place cover it with a piece of a trash bag then squeegee as much resin out as you can. the glass is the strength the resin holds it together

part one

part 2
 

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DwayneSpeer is correct. In my defense, in Step#1 where I indicate that a taper is to be made, Dwayne's suggestion is what I was getting at but did not adequately describe. I didn't have an exact ratio in mind, either 12:1 or 15:1 but something along those lines. Either way, it's easy to draw a 4.5" "target" circle and grind to the circle.

I really don't think that roving is that hard to wet. Using gloves, dip it into a tray or similar container with epoxy until wet. I suggested roving because it is stronger and builds quickly.

I wouldn't leave the transducer in place. I did that on our last boat and it was a mistake. The o rings will eventaully dry out and a leak is waiting to happen. Much better to do the job right and debate these details, IMHO.

Thanks guys, for the suggestions. This is what makes Sailnet great. I was not aware of the ratios even though I've done this job and other similar jobs in boatyards and my own boats for nearly 30 years. We always made a taper, but not to a specified ratio. In retrospect, we were pretty close but relied on eyeballing it.

Thanks.... learned something new again. :)
 

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Following this repair method will result in a very week spot in your hull that could pop out under severe weather conditions. Don't do it! Do it right or hire it done by a professional! Doing it right involves grinding the hole back at a 12 to 1 ratio. That means that for your 3/8 inch thick hull the outer edges of your ground out area will be 4.5 inches away. Then gradually build up with larger and larger pieces of fiberglass roving until the final piece is the full 10 inches diameter. Actually Ferenc Mate says in his book "Shipshape, The Art of Sailboat Maintenance" that if the hull is greater than 1/4 inch thick then the ground out ratio should be 15 to 1 but everyone else that I've read recommend only a 12 to 1 ratio.

The rest of Sabreman's recommendations are quite good. That is cleaning the area very well, etc.

Yes +1 on this.

You HAVE to "taper" out the hole both sides to get good ahdesion of fibreglass to hull. 12:1 is a minimum to spread the load.

when "laying up multiple layers of glass yo can lay them up in mulitble layers in one hit! Polyester will try quickly so ensure that you do this quickly and compress as you go to remove air.

It is also important to ensure that is the hull is layed up using epoxy that you use epoxy for the repair. I suspect it will be polyester and thus polyester, vinylester and epoxy resins will be ok.
 

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Following this repair method will result in a very week spot in your hull that could pop out under severe weather conditions. Don't do it! Do it right or hire it done by a professional! Doing it right involves grinding the hole back at a 12 to 1 ratio. That means that for your 3/8 inch thick hull the outer edges of your ground out area will be 4.5 inches away. Then gradually build up with larger and larger pieces of fiberglass roving until the final piece is the full 10 inches diameter. Actually Ferenc Mate says in his book "Shipshape, The Art of Sailboat Maintenance" that if the hull is greater than 1/4 inch thick then the ground out ratio should be 15 to 1 but everyone else that I've read recommend only a 12 to 1 ratio.

The rest of Sabreman's recommendations are quite good. That is cleaning the area very well, etc.
Totally agree.
 

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first only use epoxy, once the polyester in the hull cures the patch is only a mechanical glue joint and epoxy is many times stronger than polyester in that respect.

also you dont add cloth and add larger pieces, you largest piece should be the first one put on, it gives the largest contact to the largest piece. if you start small the largest piece is only glued to a smaller piece.

to saturate the cloth, mix the resin. then put down some plastic, put down the first layer of glass pour on some resin spread it around with a squeegee. add another layer of glass and do the same. you dont want to dip the glass in resin it adds too much resin to the glass, the best hulls have something like 30 % resin by weight, the best you can really hope for by hand is 50% resin.
 

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Discussion Starter · #14 ·
Drilled hole in Hull repair

Thanks guys for all the information. From what I understand, I need to make the hole larger, to about 4 1/2 inches diameter minimum. I need to taper the inside and outside of the hole. So just for clarification, I work from the outside first so I would tape something like wax paper to the inside so I'd have some initial barrier to work against. This is where I'm confused. What next???
 

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watch the video

sorry you will get it if you watch the video

you do not need to make the hole bigger. the smaller the better

with a one inch hole you dont really need a backer. but if you want even a piece of duct tape on the inside would do.

if the glass is 3/8, grind out about 4 to 5 inches in taper so the inner edge where the hole is a knife edge. the taper will go from very thin to just taking off the gel coat. then you will need about 8 to 10 layers of glass ( 7 oz ) the fist layer is the full size of the taper ie about 10 inches. thats the one inch hole plus 4.5 inches each side. cut each smaller piece of glass about 1/2 inch smaller. so the first circle is 10 inches, the second 9.5, third 9 inches etc.

spread some plastic ( trash bags work ) out on a table, mix the epoxy. put the smallest piece of glass on the plastic, pour on a little epoxy and work it in with a squeegee, put the next bigger layer of glass centered on the first. add a little more epoxy and work it in. keep going until you put all layers of glass with epoxy all centered, smallest to largest. take a little epoxy and mix with collidal silica and brush that around on the hull where the taper is. this epoxy layer fills any grinding grooves so the glass will not have to. then pick up the plastic with the glass and resin on it. place it over the hole so the last and largest layer is against the hull, and make sure its centered. then use a squeegee to work the glass to the hull, do not remove the plastic bag yet. work out as much resin and air as you can, then let it cure over night.

the next day, pull the plastic and see how close you are to a level surface. if you need you can add some more glass to build it up. when its close ie around 1/8 inch to level let it all cure. then mix some epoxy and light weight filler to a thick paste and spread it out. then sand smooth when cured.

you can use gel coat to cover this to protect it from then the sun.
 

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Discussion Starter · #16 ·
Drilled hole in Hull repair

OK, I got it. Fully understand and I will repair the hole this week. Thanks everyone again for your advice & help and thanks Scottyt for the videos. Somehow I missed them when I read the responses. Sorry. You're a great bunch of supporters and novices like me really depend on you. I'll post some pictures when completed.
 

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even better than just posting competed pics is to post pics of each stage, others here in the future will love that
 

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then pick up the plastic with the glass and resin on it. place it over the hole so the last and largest layer is against the hull, and make sure its centered.
Don Casey recommend the opposite approach in his book which actually sounds reasonable.
Since you are working from the outside and have a one inch hole on the inside flaring out to a 5" scoop it makes sense to start with a patch slightly larger than 1" and use slightly larger patches until you build out to the last patch being 5". The West video shows the opposite. Starting with a 5" patch that sort of bags in and each patch being smaller then ending up with the smallest on top. It looks back wards but the advantage is that more fiber is in contact with the patch.
I contacted Don about this and he said he ran tests and the West way (Scotty's way too) is stronger so he is changing his book.

So scotty is right even on this detail.
 

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OK, I got it. Fully understand and I will repair the hole this week. Thanks everyone again for your advice & help and thanks Scottyt for the videos. Somehow I missed them when I read the responses. Sorry. You're a great bunch of supporters and novices like me really depend on you. I'll post some pictures when completed.
What will likely be surprising is the number of layers that it will take to build up to 3/8 thickness.
Also I'm not sure I would attempt to do all 3/8" in one big bloop. If you are working upside-down which I suspect you are it will want to droop out.
I would probably do a patch with maybe 5, 6 layers and apply it and let it kick, making sure it is stuck up there. Then do some more layers and stick them up. Keep going until it looks good. Then hold a piece of plastic and squeegee etc.
If epoxy gets too thick it will actually get hot and start to smoke if it kicks all at once.
If others have done 3/8" in one big patch with no problems either drooping out or getting too hot I'm sure you will get some first hand accounts.
If it is you first experience with epoxy as long as you put the second coat on while the first coat is still tacky you will still get the good chemical bond.
And it may be a little easier to see how it is coming along.


Another point is that you want the glass just whetted out. The goal is to use as little epoxy as possible without leaving any dry glass.

Also thickening the epoxy with colloidal silica may be necessary to make it sticky enough to hang upside down.
 
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