Through hall installation question!

[N2Orbit]

How do you properly drill and taper a hole in the fiberglass for a 1" flush mount through hole fitting? The mounting surface looks like a giant counter sink bolt.

[WakeSlayer]

RE: Through hall installation question!

I HATE drilling holes in my boats.

You want to drill from outside in, in my opinion.
Measure. 10 times, and then double check those measurements. Again.
Get a good quality new holesaw the exact size you want. Masking tape over the area. take a small bit and get your pilot run for your hole saw. I would use a fully charged cordless 18V driver. Use steady even pressure and let the drill do the work. After that, get a dremel or something of the like to take the outside gelcoat edge of the inside of the hole. Like 1/16" --> 1/32". You could also file this with a round file, or even sand it off.
I would use 3M 5200 to put the thruhulls in.

Don't forget to measure carefully. Don't forget to measure carefully.

[djbartholomew]

RE: Through hall installation question!

I saw a post think last year on here that said to use a magnet(on the out side of the hull) and a small piece of steel (on the inside) to get a good look at that where your are drilling. Good luck

[bchesley]

RE: Through hall installation question!

Slayer is right on all accounts, but I want to add one thing. ALWAYS start drilling in reverse with a hole saw until you get thru the gel cote. You risk chipping the gel if you dont do it that way. Once you get through the gel coat then switch the drill to forward and continue on. I put three new thru hulls in my boat last year and its pretty easy. Just go slow and measure twice!!!

[N2Orbit]

Drilling a hole and measuring is no problem for me, I wanted to know if anyone had any suggestions on how to flush mount this odd shaped through hall fitting. It ha a a flat spot in the center portion then tapers(beveled) on the edges to mount flush. I have never seen anything like it. I wish it was a normal through hall fitting.

[Sinkoumn]

Aha, Thru-hull fitting :grin:

Do you have a picture of it? I am drawing a blank from your description of it. All I did to bevel the edges of the newly drilled holes was use some sand paper and a sanding block. But that doesn't help answer your question. Try and find a photo of it, or just take a quick photo of it and upload it so we can take a look at it.

[WakeSlayer]

You are not going to really be able to countersink into your hull. The fitting needs to be flat. I also like the idea of drilling the beginning of the pilot in reverse at first.

The magnet and steel idea is smart to use. in this instance, i feel you have a bunch of room so you "should be" safe.

I had an incident when my perfect pass was installed a few years ago, that this method would have been extremely wise to use. This is my frist time discussing this publicly. My name is Mike, and ......

In my defense, I did not drill the hole, and told my buddy who had no problem doing so to measure 2 million times. Well, he said he was confident. The hole got drilled and was off by about an 1/8" towards the transmission mount. This prevented the top of the PP thru hull from clearing the mount in order to thread the ring on thoroughly. The solution was to make a washer out of a cutting board to put on the outside. After that it would clear perfectly.
This cutting board is now known as the Super Air Repair Kit, I keep this around for any future emergencies.

Don't forget to measure carefully. Don't forget to measure carefully.

[wake_fun]

You can view my P.P installation in my signature for the magnet trick.......................like everyone said, measure, measure, measure, tape outside, drill in reverse through gelcoat...........

[Sinkoumn]

^wake_fun, you forgot the most important item for drilling a hole in the boat - case of beer with one beer already cracked open Yellow_Flash_Colorz:

[WakeSlayer]

Measure and drill first. Then have two beers.