Cutting centerboard slot

[Alan Peck]

What technique do you use to cut a centerboard slot? The slot in question is 1 1/4 inch wide and the apron to be cut is only 5/8 inch thick. Of course the slot must be absolutely straight and uniform.

What's the best way to do this? It will be cut after the apron is installled on the hull.

Thanks

[Jay Greer]

Build a plywood router jig. Mark center on both keel and pattern as well as the ends of the slot. Tack it to the keel plank. Cut using a plunge router with a straight bit and a base plate guide. Make light cuts till the slot is finished.
Jay

[Jim Ledger]

Here's a good example of what Jay's talking about....


http://www.woodenboatvb.com/vbulleti...ad.php?t=61115

[Thorne]

For some reason I can't find Bob Smalser's excellent "web article" on restoring the gunning dory, but that's what I used when cutting my CB slot in my restored Chamberlain dory skiff.

Bob's recommendation for using epoxy and glass cloth in the slot are also good ones -- this is where the CB rubs on the CB slot, and also where the water can get in between the false bottom (if you have one), the bottom, and the CB case/bottom plank joint. Whatever you use, seal this well!

I used a flexi sealant (Vulkem116) to join the CB case to the bottom, but in retrospect could have gone with epoxy or another harder adhesive.

If you don't have or like using a plunge router, you can tack similar guides on the bottom for a circular saw cut. Can't do the ends of the slot that way, but a handsaw and/or chisel should finish them just fine.

[Eric Hvalsoe]

I also have a router jig to make the finish trim cut. The jig is 3/4 ply run on the table saw to insure a straight slot. Take most of the slot on the part out with a jigsaw, then finish with the flush trim bit. I set my cases with Boatlife. I also run a small groove around the base of the case to insure a gasket effect with the bedding compound. For a new boat the slot in keel and apron are cut on the bench.
Eric

[Ron Paro]

I would measure and mark the location of the slot, then use a 1 1/4" forstner drill bit to drill a hole on the inside of the marks on both ends of the proposed slot. Then I use a mini dozuki panel saw to hand cut along the straight lines on the sides of the slot. This provides minimal set-up time, excellent control and a very clean cut.

Below is the result of using this method on my skiff:



Here is an image of the saw from the Woodcraft site.


http://www.woodcraft.com/family.aspx?FamilyID=4237

Ron
http://jimmyskiff.blogspot.com

[Ron Paro]

So... just curious, does anyone else cut the centerboard or dagger slot with a drill and a handsaw?

[Chan]

Ron
The drilling part sounds like a great idea, I'd be inclined to finish the cut with a circular saw.

[Daniel Noyes]

I instal the centerboard box then take a long drill bit (or a pice of rod stock sharpened at the end) and drill two holes, connect the holes with a saber saw ( dont cut into the box sides) then clean up with a rasp
Dan
http://dansdories.googlepages.com

[marsbar]

Here is my setup:

[Don Scott]

Ron,

Yes, I used a drill and a Japanese 'tsubasa' pull saw to cut the very long centerboard slot in my 16' Melonseed bottom. That method is very low tech but with a steady hand you can get a beautiful straight cut with these saws. Also, If you are using epoxy for the 'sticky' bit there is no need for absolute precision because the epoxy will take care of it. Just make sure you use more than enough filler in the glue up. I use a mix of silicon powder and dust from my sander to make this to a consistancy of peanut butter. You've got to ensure that you have plenty of ooooooooze out.

Cutting holes in the bottom of a boat after months of careful building is something of a trauma but after you have done it you wonder what all the fuss was about. All I can say is measure seven times...double it and then cut once. You can take a few days over the measuring and sort of sleep on every two or three measurements but, I'll bet that once you start cutting you will not take a break !!!

[gert]

the router has a "patern bit"

[Brahm Thexton]

Heres a small video we took for our blog when we were cutting the centreboard case slot for the Newfoundland Trap Skiff we were building.

http://hilmark-brahm.blogspot.com/20...1_archive.html

[S B]

I realize this was an old thread, but a newfoundland trap skiff "doesn't have a centerboard".

[Thorne]

"this one does" -

[S B]

Nice looking boat, but appears to be about 8 to 10 feet too short to qualify as a trap skiff.

[Thorne]

Tell it to these folks -
http://www.duck-trap.com/dtw.html


19'-11" Newfoundland Trap Skiff
Thank You
Launched July 2002

[Steve Lansdowne]

Router will work, but so will a Skill saw. I cut my Melonseed (flat keel) centerboard slot when the boat was inverted using a Skill saw with a strip of wood as an edge guide that was screwed to the keel to keep the saw in line, then finished off with a keyhole saw, then moved the guide and did the other side. Not a biggie -- just do advance preparation to make sure the hole is where you want it. I suggest figuring out where the slot goes when the boat is rightside up, then drilling very small holes (use your tiniest drill bit) at the four corners of the slot to help you set up your guide.

[S B]

Let me put it this way, I fished from one. My father, grandfather and so on hauled a trap with one. It would seem more reasonable for them to explain why the are calling it a trap skiff.