Installing Cowl/Dorades

blahman · 12-08-2007, 21:05

Hi all,

I plan to install four dorade boxes with 4" (tube area) cowl vents. I'm curious what the best route is for boring 4" holes in my cabin top. It is a plywood cored fiberglass cabin with fir headliner lamintated to the cabintop.

I appreciate all input!

Fair leads,
Aaron N.

GreatKetch · 12-08-2007, 22:43

Some random thoughts for your project:

It is by far best to use a hole saw insead of a saber saw.

Start cutting from inside so you don't splinter the wood headliner. Once the pilot bit penetrates the deck, take the drill outside and use the pilot hole to finish the 4" hole from the outside. This will give you nice clean holes inside and out.

After you have the hole cut out, rout out the deck coring for 1/2 to 1 inch back from the edge of the hole. With a plywood cored deck I'd probably use a dremel tool to do this, but good sharp chisels would work if you are careful. Replace the plywood removed with highly thickened epoxy. This will keep water from contaminating your core and causing you no end of trouble.

I think those are the key points. Somebody else might have something to add...

**GordMay** · 13-08-2007, 04:53

For larger holes, use a Hole Saw (I prefer Carbide-Tipped) or Adjustable Beam Circle Cutter.

Pericles · 13-08-2007, 05:25

GordMay,

The correct method A seems counterintuitive, so thanks for posting that.

Who is the manufacturer please?

Pericles

**GordMay** · 13-08-2007, 10:57

The recommended method A seems counterintuitive, to me as well.
“A” Correct: Blades cut inside and outside
“B” Wrong: Blades cut only inside
“C” Wrong: Blades cut only outside
Goto:
Circle cutter 30 - 300 mm

Most beam & gouge circle/hole cutters only have a single tool.

blahman · 13-08-2007, 12:54

Gord,

You're knowledge seems endless!

The circle cutter seems like it may not have enough depth to go through, though I imagine there are different types.

I had assumed a hole saw would be the way to go, but figured it's worth asking to be sure. I'd rather feel stupid than be stupid.

Thanks for your help!
Aaron N.

Pericles · 13-08-2007, 16:58

GordMay,

Thanks for the Dieter Schmid details. They have some interesting jack planes in their ranges.

Pericles

12-08-2007, 21:05	#1
blahman Registered User Join Date: Jun 2006 Location: Charlotte Harbor, FL Boat: Westsail 32 Posts: 125 Images: 50	Installing Cowl/Dorades Hi all, I plan to install four dorade boxes with 4" (tube area) cowl vents. I'm curious what the best route is for boring 4" holes in my cabin top. It is a plywood cored fiberglass cabin with fir headliner lamintated to the cabintop. I appreciate all input! Fair leads, Aaron N. __________________ "Only those who see the invisible can do the impossible." W32 #482 - Asia Marie

13-08-2007, 04:53	#3
GordMay Administrator Site Administrator Join Date: Mar 2003 Location: Thunder Bay, Ontario - 48-29N x 89-20W Boat: C.L.O.D. (Cruiser Living On Dirt) Posts: 9,337 Images: 230	For larger holes, use a Hole Saw (I prefer Carbide-Tipped) or Adjustable Beam Circle Cutter. Attached Thumbnails Attached Images __________________ Gord May ~~_/)_~~ (Gord & Maggie - "Southbound") "If you didn't have time/$ to do it right in the first place, when will you get the time/$ to fix it?"

13-08-2007, 10:57	#5
GordMay Administrator Site Administrator Join Date: Mar 2003 Location: Thunder Bay, Ontario - 48-29N x 89-20W Boat: C.L.O.D. (Cruiser Living On Dirt) Posts: 9,337 Images: 230	The recommended method A seems counterintuitive, to me as well. “A” Correct: Blades cut inside and outside “B” Wrong: Blades cut only inside “C” Wrong: Blades cut only outside Goto: Circle cutter 30 - 300 mm Most beam & gouge circle/hole cutters only have a single tool. Attached Thumbnails Attached Images __________________ Gord May ~~_/)_~~ (Gord & Maggie - "Southbound") "If you didn't have time/$ to do it right in the first place, when will you get the time/$ to fix it?"

13-08-2007, 12:54	#6
blahman Registered User Join Date: Jun 2006 Location: Charlotte Harbor, FL Boat: Westsail 32 Posts: 125 Images: 50	Gord, You're knowledge seems endless! The circle cutter seems like it may not have enough depth to go through, though I imagine there are different types. I had assumed a hole saw would be the way to go, but figured it's worth asking to be sure. I'd rather feel stupid than be stupid. Thanks for your help! Aaron N. __________________ "Only those who see the invisible can do the impossible." W32 #482 - Asia Marie

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12-08-2007, 22:43	#2
GreatKetch Registered User Join Date: Jun 2006 Location: Sausalito, CA Boat: Northstar 80/20, Fetchin' Ketch Posts: 362	Some random thoughts for your project: It is by far best to use a hole saw insead of a saber saw. Start cutting from inside so you don't splinter the wood headliner. Once the pilot bit penetrates the deck, take the drill outside and use the pilot hole to finish the 4" hole from the outside. This will give you nice clean holes inside and out. After you have the hole cut out, rout out the deck coring for 1/2 to 1 inch back from the edge of the hole. With a plywood cored deck I'd probably use a dremel tool to do this, but good sharp chisels would work if you are careful. Replace the plywood removed with highly thickened epoxy. This will keep water from contaminating your core and causing you no end of trouble. I think those are the key points. Somebody else might have something to add...

13-08-2007, 05:25	#4
Pericles Registered User Join Date: Jul 2007 Posts: 38	GordMay, The correct method A seems counterintuitive, so thanks for posting that. Who is the manufacturer please? Pericles

13-08-2007, 16:58	#7
Pericles Registered User Join Date: Jul 2007 Posts: 38	GordMay, Thanks for the Dieter Schmid details. They have some interesting jack planes in their ranges. Pericles

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