Enlarging a 7/8" hole to 1"?

[Alan Rutherford]

I had a bad experience with electricity as a kid and avoid working on anything electrical as much as possible. BUT, I would rather try to connect 440 volts to something than ruin a boat. I would find a way to make a plug rather than drill a hole.

It's part of the joy of boat ownership. You know how they say owning a sailboat is like sitting in a cold shower tearing up $20 bills ($100 for big sailboats)? A lot of those $20 (or $100) bills go for stuff that attaches to the boat and you gotta drill holes to do that. He's getting off easy. Only one hole, it's already there, and only part of a $20 bill.

Can you guess what happens when you drill a hole in the bottom of a 27' fiberglass sailboat to install a speedometer sensor while the boat is sitting in the water? You'd think the water would squirt up to the cabin roof and get all over everything and sink the boat but it doesn't. The water inside can only squirt as high as the water outside the boat. If the hole is say 10" below the waterline it can squirt 10" high at most. If you're ready to fish the lead wire for the sensor through the hole you only get a few gallons of water in the boat. The other lesson I learned that time was if you plug too many extension cords together you burn out your drill. That was before cordless. Fortunately I finished the hole first. But that's getting off the subject.

I've drilled a lot of holes in boats, torn up a lot of bills doing it, and it was very rewarding some of the time. Can't say I'm anxious to do it again though.

[Bill Dufour]

Make the 7/8 plug with a center hole for the hole saw pilot bit. Only thing is taper the plug so it does not push through the existing hole and lose register while drilling. Not the plug does not have to very accurate as long as it bears on at least three points more or less evenly spaced. Four may be easier to make on a jointer, table saw or bandsaw.
Bill

[Lee DeRaud]

Step drill bit: https://www.amazon.com/HUELE-Titaniu...df_B06Y25PFMZ/

That's certainly the right tool for the job. $9 sounds pretty cheap given that the alternative is bugger up the hull, buy the stuff to do a fiberglass repair, and then drill a new 1" hole.

[lowell holmes]

If the boat is a keel boat that stays in a slip, take it to a yard where they can haul it out for you.
I am speaking from experience having owned a 34 foot sloop. It had an auxiliary motor in it and it developed a leak at the shaft hole.

[Roger Feeley]

I've run up against this a number of times. Here's what I do.

Find a hole saw that produces a 7/8" plug and drill out a few plugs.
Put the 1" hole saw on your drill using the same pilot bit.
put the plugs onto the pilot bit as needed so you now have a 7/8" pilot
Drill a bit from both sides to avoid tearout then drill through using the pilot.

[Alan Rutherford]

This is an incredible amount of angst over what should be a small problem. There must be a million small boat drain-plug fittings. First he needs the replacement fitting, then he can find a way to attach it to the boat, which should not be difficult.

What he should NOT do is make a tapered plug for the existing fitting or the hole it was in. The plug for the hole should screw in or twist-lock. Although drains are normally above the waterline, things happen and you don't want the plug to fall out.

Note the flange and ears on the old fitting. The old bolt holes will be a bigger problem than the drain hole if the new ones don't match, especially if he's also drilling the drain hole bigger. Of course it's possible the old fitting was just held in by caulk but that's not a good idea.

Assuming he finds a new fitting and it requires a bigger hole, the hole can be enlarged with a rasp. If it's less than perfect, any gaps can be filled with the caulking the whole thing should be bedded in when it is bolted in place. In fact, it's better if there is enough gap between the hole and fitting to allow caulking to push into that gap, rather than a precise fit between fiberglass and nylon.

[Tom M King]

If the boat is a keel boat that stays in a slip, take it to a yard where they can haul it out for you.
I am speaking from experience having owned a 34 foot sloop. It had an auxiliary motor in it and it developed a leak at the shaft hole.

That's why they say "Leave it in the water, and it will get wet". This is about a Precision 15 plug. No need for a yard to haul it, or most of the other advice.

[James Waldron]

If the boat is a keel boat that stays in a slip, take it to a yard where they can haul it out for you.
I am speaking from experience having owned a 34 foot sloop. It had an auxiliary motor in it and it developed a leak at the shaft hole.

Reading your posts about your various disasters on all manner of subjects, I think I'll pass on sailing on your boat, Lowell. Wouldn't want to get my Topsiders wet!!!!

[Jim Koepke]

Reading this thread has been interesting for me. The highway to town from my home runs along the Columbia River. During the past month or so there has been a boat anchored in the middle one of the navigable inlets off the river. At first it had a blue tarp under it and up the sides. Recently the tarp was removed. When traveling to town with the wife we would wonder about the boat, why there wasn't any name on it and other things.

A few days ago when we were driving into town, there was only a little bit of the boat above water.

This gives me great pause in thinking about a quick fix for any boat related repairs.

jtk

[lowell holmes]

If you go offshore in a sloop, you will surely get your feet wet.
OBTW, we crossed the Gulf of Mexico both North-South and East-West.
We crossed the Gulf four times.

[Wade Lippman]

While I was working on a winter boat cover today, a professional fiberglass repairer happened by.
He said he would use a step drill to enlarge the hole, except that I can't enlarge the hole. It is too close to the bottom and I don't have and extra 1/16" there.
He would hold a 1" hole saw at an angle, using the bottom of the existing hole as a guide to start it, and cut a new 1" hole; so it would be the same as the old hole at the bottom and 1/8" higher at the top. However, he assured me he could find a 7/8" drain plug.

He also thought the framework for the boat cover I was building was the dumbest thing he had ever seen; why didn't I just spend $100 and have it shrink wrapped. Well, the lumber was $20 and the tarp was $20, and I can use it for many years. Sure, but what about the hours I put into it. I tried to explain it was hobby and I enjoyed building things; but he just walked away shaking his head. The unretired will never understand.

[Jim Koepke]

The unretired will never understand.

People often wonder why an hour of my time is spent on fixing something that could be replaced for a low price. They never seem to realize it would take me at least an hour to make a trip into town and back.

Being retired and living over ten miles from the nearest store changes the way you live.

jtk

[Tom M King]

Here you go. Looks like the original is so hard to find because the design was updated. A google search for "drain plug requires 7/8" installation hole" found it.

http://www.apsltd.com/rwo-screw-in-d...AaAqEREALw_wcB

edited to add: I was thinking it was the same inner hull plug that Lasers used, so a google search for "laser inner hull plug" turned up this:

http://www.apsltd.com/rwo-1-4-turn-d...lete-assy.html

[Osvaldo Cristo]

I bought a used fiberglass sailboat. It has a 7/8" drain plug that is missing the stopper. I can't find any 7/8" plugs, so I am going to replace it with a 1" plug. That obviously requires me to enlarge the existing hole. On a drill press that would be easy, but getting the sailboat on my drill press would be tough.

I have two ideas...
1) Draw a 1" circle over the existing hole and enlarge it with a multitool. My experience is that multitools are not particularly precise, so I m reluctant to do this.
2) I have a cove router bit that has a full diameter of 1". Put in a drill, it should self center in the 7/8" hole and then enlarge it to 1". Or maybe not.

Comments or other ideas would be appreciated.

Or, I could fiberglass over the existing hole and put a new one elsewhere. I have a brad point carbide 1" drill.

Yours is the classical application for step bit if it is in a flat surface. I think the thickness of the material to be drilled is not bigger than the "step" of the bit...

Good luck in your project!

[Tom M King]

Reading is at such a premium here.

This is funny. We have two Lasers here. I went out, and checked, and that white, bayonet version is indeed the inner hull plug. Both of ours could stand to be replaced. Thanks for posting the original thread. I'm ordering a couple of the newer design, and it might have saved us some missed sailing time this Spring. I'm sure I would have overlooked them otherwise.