Keel repair.

[burgundyben]

The boat is a 1963 Fairey Huntress, she has been sat on a trailer for 18 years, the method of supporting the boat was complete wrong, all the weight on the centreline where in fact the factory drawings show that they should be supported by thwartship bunks out to the chines.

The hull is a single hot moulded shell, 6 layers of 2.5mm thick veneer stapled down to a buck and backed off in an autoclave, the buck had a slot in it along the centreline, into that slot was fitted a piece of mahogany with a pair of bevels to the top (bottom when boat right way up) was fair for the veneers to sit on.

This boat has been twin outdrives, then a surface drive, then mid 90's was converted to shaft, close to the Navy spec layout, albeit with a thicker shaft and consequently a thicker tube.

I need to work out how to chop out, make up a new piece, glue and screw, then bore a new shaft hole.

 

[burgundyben]

These pics are a different Huntress, shows how the shaft log should be.

 

[burgundyben]

The bit I am least clear about is the scarf joints. They would tax the ability of my woodwork, it begs the question do I have to have a scarf or could I butt joint and put a strap over the top, perhaps the aft end the strap could be the stern log?

 

[penfold]

Has it distorted? If the hull has distorted then the keel really needs taken away completely while straightening is achieved. If not then laminating a new section in-situ should be adequate.

 

[burgundyben]

Has it distorted? If the hull has distorted then the keel really needs taken away completely while straightening is achieved. If not then laminating a new section in-situ should be adequate.

There is some distortion, but I think once the broken section is chopped out and she's correctly supported it will fall back into to place ok.

I'm fine with the concept I might laminate, but that brings with it a few questions, like, how to account for the V shape in the bottom? Machine up some wedge shapes that are the first layer laminated in?

Also, how to overlap the layers? How many layers?

Its quite a complex scheme n detail and needs to be carefully thought through.

 

[burgundyben]

This photo shows the buck, you can just make out the slot that the inner keelson was fitted into.

That's a Huntsman 28 shell being lifted off, you can see how the 23ft shoorter shell with less freeboard was built on the same buck, in fact the buck was built for the 23 and extended later.

I'm not totally new to this, I did an external keel on a Huntsman 28 about 10 years back, but that's a lot more simple!

Ultimately its me that's go to do this and its me that carries the can if its no good! But I'd like to draw upon as many different opinions as I can.

Since I'm going to leave the P bracket in place I at least have a starting point for re-drilling the shaft log.

 

[Hacker]

Not sure from the pictures exactly what you are trying to achieve. If the scarf is problematic then would a half lap work? At least that would give you a similar glue area. A butt joint sounds like a bad idea. If you were to go along the laminate route couldn’t you do a full thickness/width section and then plane to shape?

 

[penfold]

There is some distortion, but I think once the broken section is chopped out and she's correctly supported it will fall back into to place ok.

I'm fine with the concept I might laminate, but that brings with it a few questions, like, how to account for the V shape in the bottom? Machine up some wedge shapes that are the first layer laminated in?

Also, how to overlap the layers? How many layers?

Its quite a complex scheme n detail and needs to be carefully thought through.

I didn't really answer your question; I think it does have to be scarfed. Assuming it does relax into its original shape then treat one planing surface as the working face for the laminates, with edges chamfered as required. Thus;

I guess you'd be best laying it up in place to glue but with cling film or other release agent so it can be removed for final shaping and then refitted. The scarfs would be tricky to shape as the lower ends would need to be faired out to avoid a stress raising kink, a convex plane or similar may be needed.

To remove the damaged keel; other than going at it with chisels, maybe a multitool to separate the hull and keel or plane it away with a power plane?

I suppose if you were Leo Goolden you could shape a replacement keel section from solid wood and scarf it in, but I'm assuming you're just a mere mortal with woodwork.

 

[burgundyben]

"mere mortal with woodwork" is generous at best.

 

[Keith 66]

A butt joint or half lap is just about the worst joint possible to use in that location even with a strap. A scarf joint isnt that hard, It needs to be long, 12:1 ratio, In that location easiest way would be mark sides, cut nearly down& chop as much waste away with chisel, finish off with coarse sanding disc in angle grinder, use a straight edge as you go to make sure its flat.

 

[Freebee]

do you need mahogany I am sure this old free snooker table would yield quite a bit
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[tillergirl]

I have pondered the images for ages. I am thinking the keelson is saveable. When the images were taken, was the boat supported to get the shape restored? I note that the seam has only 'gone' on the starboard side. Is that correct? I am wondering if the support restoring the the shape of the bottom would close the seam tightly? If so, cleaning the beading and as much as possible between the keelson and bottom, could then be reglued in conjunction to addressing the keel.

As the the keel I am thinking that the bottom of the hull has little or no rocker? If there is no rocker (i.e. shape), I would be considering cutting the keel out ahead of the shaft hole and replacing what has been removed. A nice scarf would be necessary - in theory the scarf would have the feathering externally facing aft but I admit that would be changing my skills - glued and bolted through keel, hull and keelson - probably bronze machine screws would be my choice. Iroko would be my preference.