Cutting above waterline hole in boat - SailNet Community
 5Likes
Reply
 
LinkBack Thread Tools
post #1 of 13 Old 11-19-2012 Thread Starter
Puget Sound Pounder
 
kellysails's Avatar
 
Join Date: Nov 2008
Location: Bainbridge Island, Port Madison, WA
Posts: 635
Thanks: 21
Thanked 8 Times in 8 Posts
Rep Power: 7
 
Cutting above waterline hole in boat

I am adding a secondary bilge pump sooo... I need to cut a 1" hole above the waterline for the exit fitting. What is the best type of drill bit for making a clean cut in gel coat / FRP?
kellysails is offline  
Quote Quick Reply Share with Facebook
Sponsored Links
Advertisement
 
post #2 of 13 Old 11-19-2012
Senior Member
 
Join Date: Jun 2001
Posts: 609
Thanks: 0
Thanked 8 Times in 8 Posts
Rep Power: 15
 
Re: Cutting above waterline hole in boat

Quote:
Originally Posted by kellysails View Post
I am adding a secondary bilge pump sooo... I need to cut a 1" hole above the waterline for the exit fitting. What is the best type of drill bit for making a clean cut in gel coat / FRP?

A round one.


Seriously though, a hole saw should work fine. Just make certain you have the pilot bit installed; I've seen people try to use a hole saw w/o and the results were NOT pretty. Also, when you go to make the cut you might want to make a very small (1/8") hole from the outside in, verify that everything is clear on the inside and then go back and make the actual cutout. This way if you have to relocate the hole an inch or so you can and it will still encompass the tiny check hole.
Also, after you get the pilot bit through the fiberglass but before you let the hole saw bite into the gelcoat, STOP. Reverse the drill and then CAREFULLY run the hole saw in reverse to "mark" the hole. Now drill it out normally in Forward. This trick will minimize, if not completely prevent chipping and splintering of the gelcoat. Or course the edges of the hole will be covered by the through hull, but why not make the hole as neat as possible.
Good Luck.

CS 36M DIANTHUS
sailordave is offline  
Quote Quick Reply Share with Facebook
post #3 of 13 Old 11-19-2012
Senior Member
 
chef2sail's Avatar
 
Join Date: Nov 2007
Location: Maryland
Posts: 7,088
Thanks: 30
Thanked 58 Times in 54 Posts
Rep Power: 8
 
Send a message via AIM to chef2sail
Re: Cutting above waterline hole in boat

I drill/ saw through the blue masking tape...prevents splinter of gelcoat
SloopJonB likes this.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
___________________________
S/V Haleakala (Hawaiian for" House of the Sun")
C&C 35 MKIII Hull # 76
Parkville, Maryland
(photos by Joe McCary)
Charter member of the Chesapeake Lion posse

Our blog-
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


“Sailing is just the bottom line, like adding up the score in bridge. My real interest is in the tremendous game of life.”- Dennis Conner
chef2sail is offline  
Quote Quick Reply Share with Facebook
post #4 of 13 Old 11-19-2012 Thread Starter
Puget Sound Pounder
 
kellysails's Avatar
 
Join Date: Nov 2008
Location: Bainbridge Island, Port Madison, WA
Posts: 635
Thanks: 21
Thanked 8 Times in 8 Posts
Rep Power: 7
 
Re: Cutting above waterline hole in boat

Wow, just the advice I was looking for, perfect. Now I just need to summon the courage.

Thank you very much!

-craig
kellysails is offline  
Quote Quick Reply Share with Facebook
post #5 of 13 Old 11-19-2012
Senior Member
 
rhr1956's Avatar
 
Join Date: Dec 2010
Location: Heath, TX
Posts: 490
Thanks: 1
Thanked 10 Times in 10 Posts
Rep Power: 5
 
Re: Cutting above waterline hole in boat

"Spread your arms and hold your breath and always trust your cape." -Guy Clark
rhr1956 is offline  
Quote Quick Reply Share with Facebook
post #6 of 13 Old 11-19-2012
Senior Member
 
chucklesR's Avatar
 
Join Date: Sep 2007
Location: Pasadena Md - Magothy side
Posts: 5,979
Thanks: 10
Thanked 31 Times in 31 Posts
Rep Power: 10
     
Re: Cutting above waterline hole in boat

For a 1 inch - use a fortner bit. No worry on chip out or wandering.

Drill from outside in, and blue tape.

Lessons learned are opportunities earned.
chucklesR is offline  
Quote Quick Reply Share with Facebook
post #7 of 13 Old 11-19-2012
Senior Member
 
Join Date: Jun 2001
Posts: 609
Thanks: 0
Thanked 8 Times in 8 Posts
Rep Power: 15
 
Re: Cutting above waterline hole in boat

Quote:
Originally Posted by chucklesR View Post
For a 1 inch - use a fortner bit. No worry on chip out or wandering.

Drill from outside in, and blue tape.

Sorry Chuckles, I have to disagree w/ you on this. A Forstner bit chews up everything that is inside the hole limits. A Hole saw on the other hand just makes a thin slice and you're left w/ a plug that comes out of the hole and a WHOLE lot less fiberglass dust. Makes a bigger mess, ruins your nice Forstner bit and if it "grabs" and scoots across the hull... can ruin a whole lot more.

I do however, "second" the use of blue tape. Meant to put that in my first post.

CS 36M DIANTHUS
sailordave is offline  
Quote Quick Reply Share with Facebook
post #8 of 13 Old 11-19-2012
Just another Moderator
 
Faster's Avatar
 
Join Date: Sep 2005
Location: New Westminster, BC
Posts: 16,534
Thanks: 104
Thanked 310 Times in 300 Posts
Rep Power: 10
     
Re: Cutting above waterline hole in boat

Have to go with sailor dave on the Forstner bits.. I used several on a recent project.. they work great for clean holes and cut better than the average holesaw, IMO, but they do make a mess. For single skin or even cored glass up to an inch or so I'd go with a holesaw.. I was drilling through glass encapsulated 2" timbers so the depth of most holesaws was problematic, as would removing the cores have been. The Forstner bit did a good job despite the large amount of shavings.

Ron

1984 Fast/Nicholson 345 "FastForward"

".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)

Last edited by Faster; 11-20-2012 at 11:53 AM.
Faster is offline  
Quote Quick Reply Share with Facebook
post #9 of 13 Old 11-20-2012
Senior Member
 
rhr1956's Avatar
 
Join Date: Dec 2010
Location: Heath, TX
Posts: 490
Thanks: 1
Thanked 10 Times in 10 Posts
Rep Power: 5
 
Re: Cutting above waterline hole in boat

I agree with the "no Forstner" bit. They are made to bore a large diameter hole that does not go all the way through the material. Very handy when installing European syle cabinet hinges. Definately use the hole saw. Much easier and cleaner.
rhr1956 is offline  
Quote Quick Reply Share with Facebook
post #10 of 13 Old 11-20-2012
Reward for lost Kraken!
 
hellosailor's Avatar
 
Join Date: Apr 2006
Posts: 11,481
Thanks: 5
Thanked 132 Times in 129 Posts
Rep Power: 11
   
Re: Cutting above waterline hole in boat

Oh, come on guys. If you want a really clean hole in fiberglass, you find a local hospital using one a them DaVinci surgical robots, with a laser ablation attachment, and have them burn the hole for you. Off the books, at night.

Clean, round, neat, no fuss. Slip the OR tech a couple of bucks and he'll bring it down while the machine is out being "sterilized" and no one misses it.
hellosailor is offline  
Quote Quick Reply Share with Facebook
Reply

Quick Reply
Message:
Options

By choosing to post the reply above you agree to the rules you agreed to when joining Sailnet.
Click Here to view those rules.

Register Now



In order to be able to post messages on the SailNet Community forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
Please note: After entering 3 characters a list of Usernames already in use will appear and the list will disappear once a valid Username is entered.


User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
Cutting Access Hole in Stainless Steel Diesel Fuel Tank Ajay73 General Discussion (sailing related) 42 12-27-2011 08:28 PM
Small hole completly aft at waterline Bene505 Gear & Maintenance 24 03-09-2009 12:21 PM
cutting access hole xort Gear & Maintenance 27 01-04-2009 05:33 PM
Cutting a hole in the deck dawnhoff Gear & Maintenance 12 07-04-2008 09:47 AM
Cutting through hole NautiG Gear & Maintenance 12 01-08-2008 07:18 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome