Knee replacement

[Anthonyexmouth]

Ok, got a little 14' registered fishing boat and ideally need 2 knees replaced for the next survey. Now I don't have access to a band saw since mine went pop and let out the magic smoke. What I do have is plenty of stainless square tube and a tig welder, how bad on a scale of 1-10 would it be to make up stainless knees for this classic old clinker fishing boat?

 

[Hacker]

At least -1

You could cut 2 rectangles and put a half lap joint in the end to make an L-shape. That could be improved by shaping, but would be much better that steel tube!

 

[Anthonyexmouth]

At least -1

You could cut 2 rectangles and put a half lap joint in the end to make an L-shape. That could be improved by shaping, but would be much better that steel tube!

-1, hmm that's not as bad as I thought the answer would be.

 

[Hacker]

I was being nice! As a wooden boatbuilder/restorer I could live with HMWP ribs, but steel knees!

 

[Anthonyexmouth]

I was being nice! As a wooden boatbuilder/restorer I could live with HMWP ribs, but steel knees!

My other reason for considering them was that I have no cleats on the boat to avoid snags when shooting nets, thought the cross brace would be a nice easy place to tie a fender or center line.
You're more than welcome to pop up and throw a couple in for me. lol.

 

[SaltIre]

Preparing for a knee replacement operation
PM me if you want more help.

 

[Hacker]

My other reason for considering them was that I have no cleats on the boat to avoid snags when shooting nets, thought the cross brace would be a nice easy place to tie a fender or center line.
You're more than welcome to pop up and throw a couple in for me. lol.

Are they hanging or lodging knees? I guess using them as a place to tie things could justify the use of steel; obviously need to ensure the attachment is strong enough.

 

[Anthonyexmouth]

Only from a small clicker punt. Gone a bit soft in place so thinking MCA will pick up on them at the next survey

 

[DownWest]

On my faering I laminated them out of iroko, but surely you can cut those with a jig saw?

 

[Hacker]

Thwart hanging knee. Never done steel fabrication, but wonder how you would match the hull curve and tie it into the gunwale. I’d still fabricate using 2 rectangles of appropriate hardwood, angled to match the thwart hull angle and joined with a glued half lap joint (this gives you the grain in both directions). The piece against the hull will need a little bit of shaping and the piece along the thwart could be shaped with a jig saw as @DownWest suggests.

 

[Fantasie 19]

Ok, got a little 14' registered fishing boat and ideally need 2 knees replaced for the next survey. Now I don't have access to a band saw since mine went pop and let out the magic smoke. What I do have is plenty of stainless square tube and a tig welder, how bad on a scale of 1-10 would it be to make up stainless knees for this classic old clinker fishing boat?

Classic boats were once working boats.. the original fishermen wouldn't have blinked at using any available material to do repairs .. stainless wouldn't bother me, but it's your boat..

 

[Fr J Hackett]

On my faering I laminated them out of iroko, but surely you can cut those with a jig saw?

Was about to say the same thing even a hand saw followed by a spokeshave or rasp then sanded it isn't a difficult job.

 

[DownWest]

Getting back to this.. If limited to SS and your tig, Bend a bit of flat to form the base angle between the thwart and the hull, then weld a bit of tube to 'cross' the angle'. If the flat is wide enough each side of the the tube, gives room to put fastenings.
My build was epoxy only, no screws or nails.

 

[srm]

Its a working boat, not a museum exhibit, so feel free to do what you need to.

If you think it may have a future life as a plaything or museum piece please make sure that your working modification can be removed and replaced with nice looking pieces of wood when it is retired.

Lots of Shetland double enders had the stern post cut off and a small triangular transom fitted to take an outboard. Totally spoilt the look of the boat, but saved a lot of rowing and made life a lot easier for the fishermen/crofters who used them.

 

[Anthonyexmouth]

Its a working boat, not a museum exhibit, so feel free to do what you need to.

If you think it may have a future life as a plaything or museum piece please make sure that your working modification can be removed and replaced with nice looking pieces of wood when it is retired.

Lots of Shetland double enders had the stern post cut off and a small triangular transom fitted to take an outboard. Totally spoilt the look of the boat, but saved a lot of rowing and made life a lot easier for the fishermen/crofters who used them.

Essentially would be a stainless bracket with a brace, inverted gallows, fixed in the place of a knee, maybe bent over the gunwale and bolted to the thwart.

 

[Anthonyexmouth]

Cobbled something together a had a test fit after removing the old rotted knee. Leaves the boat in an easy position to replace with wood in the future.
Question is, do i bolt or use copper nails to fix the stainless knee in place.

 

[Hacker]

I’d probably used stainless bolts. Presume you are putting a packing piece between it and the planks?

A fair few of your ribs need replacement!

 

[Anthonyexmouth]

I’d probably used stainless bolts. Presume you are putting a packing piece between it and the planks?

A fair few of your ribs need replacement!

They look like they do but that's due to the paint, the ones that needed to be doubled have already been done, Once the paint is burnt off they look good. MCA were happy with it during the last survey in 2020 and only had the knees as an advisory.
Old knee was only nailed through the gunwale so undecided as to the packing. I had planned to cut the old knee straight down and use that but as it was only nailed at the top I'm thinking I'll leave it open, let some air around it. 3 fixings in thwart and on in gunwale.

 

[westernman]

Am I the only one to think that this was about body parts rather than boats when reading the title?

 

[srm]

Question is, do i bolt or use copper nails to fix the stainless knee in place.

I would suggest ss bolts with large washers or similar backing pieces. Also, copper nails through ss will probably be an interesting electrolytic mix.