Drilling holes in my deck - Help!^

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Mr Hoppy
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Drilling holes in my deck - Help!^

Post by Mr Hoppy » Tue May 18, 2010 9:04 am

I'm about to fit a cleat and fairlead onto my Alaw, whilst I'm no numpty it still seems wrong to be taking a drill to it. Anyone got any tips on how to make it seem less daunting?

Chris

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maryinoxford
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Re: Drilling holes in my deck - Help!

Post by maryinoxford » Tue May 18, 2010 10:12 am

Ask Rockpool for advice?
Not in Oxford any more...

Gages
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Re: Drilling holes in my deck - Help!

Post by Gages » Tue May 18, 2010 11:01 am

Masking tape over were your going to drill,it will help stop the gelcoat from chipping and a nice sharp bit

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Jim
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Re: Drilling holes in my deck - Help!

Post by Jim » Tue May 18, 2010 11:23 am

Gages wrote:Masking tape over were your going to drill,it will help stop the gelcoat from chipping and a nice sharp bit
Also if you start drilling in reverse, the gel coat will be turned to powder and you will get a clean edge rather than the ripping and chipping that can occur if drilling forwards. Once through the gelcoat you can drill forwards.

Plan whatever you are backing it up with (usually a wooden pad, sometimes there is a stainless backing pad or just big washers) find a relatively flat spot and sand the wooden pad to fit the shape of the deck.

Squeeze a ring of sealant around your hole, you can put some down the hole if you want, the bolt will push it out and it will get all over the threads but it may still do some good. The ring will flatten out as you tighten the fitting down and form a gasket.

GrahamKing
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Re: Drilling holes in my deck - Help!

Post by GrahamKing » Tue May 18, 2010 12:47 pm

Jim wrote:sand the wooden pad to fit the shape of the deck
If you use double-sided tape to stick a piece of abrasive paper to the deck (abrasive side up!), you can then carefully rub the wooden pad to-&-fro to get an accurate profile.

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TechnoEngineer
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Re: Drilling holes in my deck - Help!

Post by TechnoEngineer » Tue May 18, 2010 2:36 pm

For plastic boats you'd drill the hole approx' 0.5mm undersize and tap it, to minimise the amount of water that gets in. Would you do the same for a composite boat?
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MikeB
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Re: Drilling holes in my deck - Help!

Post by MikeB » Tue May 18, 2010 3:57 pm

No need - iirc I just put some silicone on the large washers I used and never had any problems with water ingress. I was in a hurry when I fitted the kit, and didn't bother with a backing plate. Despite some serious loading on occassion, both the cleat and the bullseye have been fine on the Quest. Having seen a certain well-respected retailer fit tow kit to one of his boats, I can tell you he didn't bother with any sealant, or a backing plate either.

Mike.

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Jim
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Re: Drilling holes in my deck - Help!

Post by Jim » Tue May 18, 2010 6:02 pm

If you allow the bolt to tap the hole it won't draw the fitting down as tight as if it's in a clearance hole, the nut force will be opposed by the force in the tapped hole, not the head of the bolt bearing on the fitting.

I think it is used for polythene because the material is so soft that tapped hole just gives and you bear on the fitting anyway, and it is safer than drilling a 0.5mm clearance hole which may potentially lead to bearing issues from a lateral load on the fitting because the contact are between the bolt and hole would be smaller. It basically helps to prevent the polythene tearing out around the fitting.

All of which said the laminate is probably thin enough that it won't achieve the thread loads anyway?

Many softish plastic fittings will seal against a hard gelcoat fine, but most of us are paranoid enough to add a bit of sealant when doing it outselves, or we add it later in life when we identify a fitting as a source of a niggling drip.

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Voodoo
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Re: Drilling holes in my deck - Help!

Post by Voodoo » Tue May 18, 2010 6:48 pm

Have a look at the Cleat on my Boat next time chris see if that helps any, I assume it was done at Factory and is glassed underneath

Failing that I dont mind taking a drill to your boat, in fact I will happly disregard all above advice and just go for it :-) you can watch as well it will be fun !
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chrism
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Re: Drilling holes in my deck - Help!

Post by chrism » Tue May 18, 2010 8:34 pm

Drilling a little hole to fit a cleat? I'm considering cutting a big hole in my brand new high performance surfski (which has a sandwich construction!) to fit a hatch - I'm finding that a very scary idea.

Gages
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Re: Drilling holes in my deck - Help!

Post by Gages » Tue May 18, 2010 9:46 pm

its just as easy as a small hole but be sure to keep the hole round by fast long sanding motions ,not little ones where you can lose the round

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Blutack
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Re: Drilling holes in my deck - Help!

Post by Blutack » Tue May 18, 2010 9:47 pm

Just one thing that I don't think has been mentioned yet - if you decide to use rubber sealant, it works well to splodge it about, and then only nearly tighten down the fitting. Then, if you wait until the sealant cures before tightening fully, the rubber will be squashed a little, and will form a better seal. HTH!

Edit: Oh, and re fitting the hatch, I've done one before, and it wasn't nearly as bad as I expected, since the hatch overlap will cover over any minor un-roundnesses :-)

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Jim
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Re: Drilling holes in my deck - Help!

Post by Jim » Wed May 19, 2010 10:56 am

chrism wrote:Drilling a little hole to fit a cleat? I'm considering cutting a big hole in my brand new high performance surfski (which has a sandwich construction!) to fit a hatch - I'm finding that a very scary idea.
Jigsaw with a diamond coated blade.
If you want to avoid scratches you can tape the base of the jigsaw.

Blutack - do you lace your canoes? All this worry about one small hole in the deck, many canoeists take a brand new boat and drill about 100 holes just below the gunwale all round... I reckon sea kayakers are timid :-)

Owen
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Re: Drilling holes in my deck - Help!

Post by Owen » Wed May 19, 2010 11:19 am

I wrote this blog about fitting a back hatch and bulkhead to my kayak.

http://www.ukriversguidebook.co.uk/foru ... 5&start=30

Then this one about fitting the front hatch.

http://www.ukriversguidebook.co.uk/foru ... ilit=hatch

For cutting with a jigsaw I used a blade for cutting kitchen tops (formica).

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adrian j pullin
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Re: Drilling holes in my deck - Help!

Post by adrian j pullin » Thu May 20, 2010 12:44 pm

You should try fitting side windows to a new van! - I bottled and paid someone else to do it!
Cheers

Adrian J Pullin
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Billy The Fisherman
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Re: Drilling holes in my deck - Help!

Post by Billy The Fisherman » Thu May 20, 2010 10:10 pm

An ordinary wood or metal drill bit will do and a fine bladed jig saw easily copes with GRP or carbon fibre if bigger holes are needed.
If your boat has a gel coat you should drill the hole the correct size to accommodate a bolt. Then, countersink the gelcoat to prevent spider-leg cracks developing. Reinforce the inside of the boat with a piece of wood cut and shaped to fit the contours of your boat.
For large boats, i.e. not kayaks or canoes the holes are often drilled oversize then filled with resin and redrilled with the correct drill bit size. This is especially important if the hole goes through any area reinforced with wood as a good seal is required.
When you fit the cleat, add a thin layer of silicone sealant – ideally marine sealant like Sikaflex and gently tighten down the bolts a little to bed the cleat in. Leave the sealant to dry before tightening the bolts to their final position, this helps form a better seal with the silicone acting as a gasket.

Finally, cut once measure many.

chrism
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Re: Drilling holes in my deck - Help!

Post by chrism » Thu May 20, 2010 11:32 pm

Billy The Fisherman wrote:Finally, cut once measure many.
I find it works better if you reverse the order of those operations.

mikeyak
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Re: Drilling holes in my deck - Help!

Post by mikeyak » Mon Jun 14, 2010 10:38 am

I think the expression is, measure twice and cut once.
More seriously, I am planning to do this job myself and feel it is essential to glass in a small back plate, preferably of marine ply. Once you drill a hole you introduce weakness into the drilled area and given the purpose of the alteration this is probably unwise. Best of luck.
Mike
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cj
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Re: Drilling holes in my deck - Help!

Post by cj » Mon Jun 14, 2010 12:49 pm

I would go with Mikeyak on this one. Amazing how many people fit something then discover they can't reach it or its chewed through a bouyancy bulkhead or clips an elbow or hand when paddling, jams on the J bars when you put it on the roof rack. If its a cam cleat you are fitting, can you reach it in a big sea? which hand do you want to use ie the left because you control with your right or are you hopeless with the left and have to use your right. Drilling the the hole is the easy bit.

Boots
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Re: Drilling holes in my deck - Help!

Post by Boots » Mon Jun 14, 2010 11:01 pm

Mikeya, instead of ply use an old plastic chopping board cut to your required size I did this for my plastic knordkap works a treat

Boots

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MikeB
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Re: Drilling holes in my deck - Help!

Post by MikeB » Tue Jun 15, 2010 3:06 pm

Billy The Fisherman wrote:An ordinary wood or metal drill bit will do - -
A bit for metal is best I've found - the cutting edges are angled while those for wood, (designed with a centre point ) seem to have a tendancy to catch the edges as their cutting blades are more often than not at 90 degrees to the vertical line and will chip the gel too easily.

Jim's idea of reversing the bit to make the first impression works really well.

Mike.

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delphinidae
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Re: Drilling holes in my deck - Help!^

Post by delphinidae » Tue Jun 15, 2010 5:45 pm

I've drilled a few holes in my deck, mostly using a HSS drill bit and a hole saw. As others have said, using an auger bit or a spur bit or a flat wood bit probably isn't wise.

Gelcoat and the layers of glass/resin beneath it are relatively soft materials, so you don't need to use high drill speeds.

(can't comment on appropriate backing for a load-bearing fitting like a cleat because I haven't fitted one)

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