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View Full Version : Quarter knees, fasten from inside or outside?



dmede
05-30-2008, 08:41 PM
I need to fasten my quarter knees and am looking for some help on which direction to go, screw from inside out or outside in?

Seems like the leg along the sheer would be outside in, with the screw head just buried in the cedar plank. The leg along the transom could go either way. I think it would work best from outside in, but then I will have plugs showing in my bright transom (which I don't really care about). Or I might even leave the screw heads flush and exposed on transom face? It is a work boat and I kinda like seeing some of the fasteners exposed.

What's the best way to do this?

http://farm3.static.flickr.com/2414/2537790332_7ee71a83c7.jpg
http://farm3.static.flickr.com/2367/2536973309_ab9c0150c5.jpg

silvergull
05-30-2008, 09:12 PM
In general, fastenings go through softer wood and into harder wood. Planking and decking are fastened to framing. The harder wood, often oak, has better screw holding ability than does the softer cedar, pine or even mahogany.

However, thinner material is usually fastened to thicker regardless of hardness. The greater depth or "bury" into the thicker stuff making up for screw holding ability.

Nails take this rule further since nail holding ability is usually less than a material's screw holding.

Hot dipped galvanized nails into oak might be an exception. Most stubborn fastenings.

Your fastenings go into the knee

Cheers, Jim

Wooden Boat Fittings
05-30-2008, 09:31 PM
.
I'd put two rivets right through each knee from both sides-- ie two through the sheer strake and knee and two through the transom and knee.

Quarter-knees, like breatshooks, are there to provide strength and rigidity to offset the wracking strains produced in the hull by wave action. The stronger you can make these corners the better. Screws or nails are simply not as strong as rivets.

Mike

BillyBudd
05-31-2008, 05:46 AM
Exposed fastenings or not, what's wrong with also some epoxy not only in the joint, but also a structural fillet on the underside?

silvergull
05-31-2008, 06:14 AM
I like the rivets; in each arm of the knee. In the corner of the transom/planking meeting, I would go with screws. Remember, rivets need properly sized holes lest they "cripple" in the wood.

Given the grain orientation, epoxy in the joints and as a bead on the underside should not cause immediate harm. Makes taking the knee out a destructive process should the topstrake or transom ever need replacement due to damage from impact or rot.

Cheers, Jim

merlinron
05-31-2008, 08:33 AM
at the transom, i would think a couple good fitting plugs would be small price to pay for the security of fastening from the outside-in with screws. it looks like you have ample thicknes for a good length of screw, there, and in the corner (heal of the qurter knee) of the sheerstrake to knee joint, again, outside-in. and then a rivet or two in the leg, at your marks, along the sheerstrake. screws might look better in these two spots (along the sheerstrake), but being a workboat, rivets will hold on better there. you might counter-bore the rivits on the inside of the knee along the sheer strake, so they don't stick out and catch on everything, unless you can peen them down nice and smooth.
as mentioned, it's a spot that might need rework at some time and using some epoxy will make a fairly easy replacement destructive.

Mrleft8
05-31-2008, 08:44 AM
Outside in, and plugs to match your transom. Bed the knees in Dolphinite or other bedding compound. I'd stay away from epoxy if you ever need to do a repair you'll know why.
Nice looking knees BTW! ;) Easily worth a bottle of Hopland brewery, or Buckthorn brewery's best! :D

dmede
05-31-2008, 10:26 AM
No epoxy! Who said epoxy!? :D

They will be bedded with some PL Weather-strip Sealant (not the PL Premium Glue), acts just like 3m5200 with a little less stick IMO. Very thin bed line.

I like the idea of riveting at the thinner part of the legs, one or two rivets. But I may just go for simplicity and screw in. I'm thinking of doing 3 #12 screws from outside in on each leg. I agree, the plugs will be fine and I'm not sure I'll be leaving the outer face of the transom bright anyway. Thanks for the input guys.

dmede
05-31-2008, 10:28 AM
Outside in, and plugs to match your transom. Bed the knees in Dolphinite or other bedding compound. I'd stay away from epoxy if you ever need to do a repair you'll know why.
Nice looking knees BTW! ;) Easily worth a bottle of Hopland brewery, or Buckthorn brewery's best! :D

You bet, those strips worked like magic and look pretty good all varnished up (the breast-hook has a couple coats on it). Mendo Brewing huh? You a lager guy or an ale guy? Or are you like me... a beer guy? ;)

jclays
05-31-2008, 11:26 AM
You bet, those strips worked like magic and look pretty good all varnished up (the breast-hook has a couple coats on it). Mendo Brewing huh? You a lager guy or an ale guy? Or are you like me... a beer guy? ;)


Anchor steam for me please...BTW nice knees...

Jay Greer
05-31-2008, 12:35 PM
I like fin headed bolts for fastening knees. These can be made in the shop or purchased on line from specialty fastening dealers. A die can be made by taking two blocks of steel that are doweled together and, drilling a hole down the split line that is smaller than the rod to be headed. Then a countersink is used to create a cone shaped deptression that can have wing cuts ground in with a die grinder.
Gripping the rod in the die by clamping it in a vise, allows one to heat the end with a torch and smack it into the die with a hand sledge.
It is then up to the craftsman to either thread the other end or make up clinch rings for riviting on the inboard side. I make up bronze clinch rings for small jobs on my metal lathe. Larger jobs go into making a casting pattern. Pardeys have my last pattern and will supply rings upon request.
Jay

Canoeyawl
05-31-2008, 06:34 PM
I agree with Jay,
Bolts
(this die makes three different sizes)
http://www.gunkholing.org/Images/finheadrs.jpg

Paul Scheuer
05-31-2008, 06:58 PM
You have reached another boundary of my ignorance. What's the point of the fin ? I guess I can see it serving as anti-rotation, like a rib-neck carriage bolt, but I don't see the function when riveting.

Canoeyawl
05-31-2008, 08:20 PM
You are correct sir!
There is no purpose for the fin when used as a rivet but as a bolt the fin is to resist rotation.
My little die (made with a drill press) only makes ‘em with a fin, but the head can be finished off as either flathead or carriage style depending on which side of the die is used.

Mrleft8
05-31-2008, 09:13 PM
You bet, those strips worked like magic and look pretty good all varnished up (the breast-hook has a couple coats on it). Mendo Brewing huh? You a lager guy or an ale guy? Or are you like me... a beer guy? ;)
Back in the day I'd been known to down a few ales at either Hopland, Buckthorn. Dick's (in Mendo) The Golden West, or Cal's (in Ft. Bragg) Or the Caspar Inn which was across the street from my house (In Caspar of course)..... I'm an Amber ale, IPA, Bock, Porter, Kinda guy..... There are a few lagers that have turned my head, but I like the fuller bodied brews.... Next time I get out that way, we can decide which of 3 or 4 is the best! ;)

Thorne
05-31-2008, 10:20 PM
What, those big SB screws I sold ya aren't enough?

;0 )

Surprised to not see more recommendations for epoxy, as I thought that it would be perfect for this particular application -- plus take some of the stress off the fasteners.

Sure seems like you'd end up replacing either the knee, the plank or both if you had to take the boat that far apart, so what's to lose with epoxy?