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Trying to drill a hole into SW to install zincs

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gbeardjr
Navigator

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USA
101 Posts

Initially Posted - 09/12/2006 : 17:50:52

I sail mostly in saltwater and am trying to drill a 1/4" diameter hole through my swing keel to install some zinc discs. I have purchased three different drill bits so far and have hardly made a dimple in the surface of the keel. Anyone know the zincs supposed to be installed on the keel? What kind of drill bit must be used?

There are 10 kinds of people in this world. Those that understand binary and those that don't

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ClamBeach
Master Marine Consultant

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3072 Posts

Response Posted - 09/12/2006 : 20:34:13

You've got to generate enough pressure to make the drill 'cut'. It takes quite a bit of whoopie to get even a 1/4" bit 'working' properly. (Which is why they have drill presses). You might try drilling a pilot hole with a 1/8" bit first. A cutting fluid (RapidTap etc) can help. Do NOT use regular oil, WD 40 etc.) You need more rpm for a smaller drill... slower as you go bigger. Most 1/4" drill motors will have the proper rpms for a 1/4" bit.

Over the years I've used quite a few 'jury rigs' to drill holes... 2x4's and a ropes to form a lever... helpers pushing on my back etc.

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JimB517
Past Commodore

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USA
3285 Posts

Response Posted - 09/13/2006 : 11:48:11

Cast iron is very hard. You need a carbide bit.

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ajski1000
1st Mate

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USA
52 Posts

Response Posted - 09/13/2006 : 21:27:02

Bruce has it right,

You need to create some pilot holes. I did this this spring.
Get some SS machine screws, and then use a drill bit somewhat smaller this way you ensure you have a tight fit when you put the zinc plate on. Just to make sure it held I added some sealant.

AJ

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tinob
Master Marine Consultant

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USA
1883 Posts

Response Posted - 09/14/2006 : 08:52:23

I find that COBALT drills are the boss for everything I try to drill.

As an aside, some years ago, a fellow here reported drilling right through the swing keel to attach the cable. Pictures even. Try the archives you might find his post. He was an east coaster somewhere in the Va./N.C area.

Val on Calista # 3936, Patchogue, N.Y.

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HudsonM1
1st Mate

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USA
41 Posts

Response Posted - 09/14/2006 : 20:33:16

I did this this past spring as well. I don't recall drilling a pilot hole, but I did buy 2 new carbide-tipped 1/4" bits thinking I'd burn one up. I was pleasantly surprised that as soon as the bit took hold, it plowed through the keel without too much trouble. I never needed the 2nd bit.

Use a center punch to mark your spot so the bit doesn't walk around, use lots of pressure to get the hole started, but then back off. Go slow and gentle from that point on so the bit doesn't heat up.

Good luck!
Hudson

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Happy D
Admiral

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921 Posts

Response Posted - 09/15/2006 : 08:15:12

I hate to suggest this but make sure the drill is turning the correct direction. Cast Iron is soft and should drill like butter. In fact, there is so much carbon in the type of cast iron that would be used for a keel,you shouldn't even need coolant.
The speed of the drill should be around 1000 rpm.

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gbeardjr
Navigator

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USA
101 Posts

Response Posted - 09/15/2006 : 08:35:05

I gave up I h tried five different bits not with no luck, I got the hole maybe 1/4" inch deep. I gave up and bolted a zinc with a short machine screw into this hole and used epoxy on the zinc and screw to make sure it stayed in. With the bolt there hopefully there is enough conductivity for the zinc to help.

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Bruce Baker
Captain

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USA
402 Posts

Response Posted - 09/19/2006 : 11:08:04

I drilled holes in my swing keel and mounted zincs on them too. The iron is NOT soft as butter. It took me three carbide tipped drills to drill two holes--maybe 3/4 inches deep each. I've got two big zincs--massive overkill in fresh water.

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ajski1000
1st Mate

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USA
52 Posts

Response Posted - 09/21/2006 : 16:49:50

Bruce,
Agreed, it was no east task drilling into the keel! Pilot holes did help thou :)

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oldsalt
Admiral

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USA
578 Posts

Response Posted - 09/21/2006 : 18:49:31

Bruce,

Are your "zincs" really zinc or are they magnesium or aluminum?

I'm under the impression that zinc "zincs" are only suitable for salt water and aluminum or magnesium "zincs" should be used in fresh water.

Anyway, that's what I thincs about zincs.

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Steve Siefken
1st Mate

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USA
81 Posts

Response Posted - 09/21/2006 : 22:25:25

How far into the keel do you need to drill to install the zincs?

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Dick Johnson
1st Mate

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USA
40 Posts

Response Posted - 09/28/2006 : 16:53:03

I purchased zincs from CD when I had my boat hauled out. The marina suggested that I not have them installed. With good bottom paint, it is not needed. Just his suggestion but I took it as I've had my boat in salt water for six years without zincs and no damage.

Lagniappe C-25 sk 5512 North Carolina

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stampeder
Master Marine Consultant

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1608 Posts

Response Posted - 09/28/2006 : 19:52:52

an old hand at a Navy Marina told me that zincs also help protect your boat from electrical current that tends to be in most busy marinas. Most electric devices leak some electricty and water is a good conductor.

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The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.