Mitchell 31 keel replacement

[SeaLimpet]

Looking to replace the wooden keel/shoe on my Mitchell MK1, anyone have any experience in doing this?
What sort of wood? possible with engine in situ? fixings?

Thanks for any advice

 

[Rappey]

Without more info your going to get the best guess and more questions than answers.
What size keel is it, is it all wood or grp stub. Can you see keel bolts inside your hull and are any under the engine?

 

[tillergirl]

Iroko would be good. Have you got to remove the original or can you fit a new piece over it? I don't think I saw the bolts inside - perhaps encapsulated. Best I go and look. Previous owner had fitted a steel shoe over the timber keel, screwing into the wooden keel.

 

[Jcorstorphine]

50 years ago, I fitted out a 21 ft motor cruiser / sailer from bare mouldings. Part of the work included the fitment of an external wood keel. The wood I used was Keruing which is a hardwood often used on heavy duty trailers. I used 3 lengths of timber glued together to give me a 6 inch keel. I constructed the keel in two sections with a staggered joint. This made the fitting of the pre assembled keel sections in place easy as I could support the boat while fitting the half sections in place. Once the two section of the keel were in place I drilled half inch bolt holes using a hand auger. I used standard galvanised coach bolts which I heated with a blow lamp and then coated with bitumen paint. I saw the boat recently as it was out of the water for refurbishment and the keel still looks in pretty good condition.

 

[SeaLimpet]

Without more info your going to get the best guess and more questions than answers.
What size keel is it, is it all wood or grp stub. Can you see keel bolts inside your hull and are any under the engine?

The keel is fibreglass & part of the hull, lower wooden shoe is approx 4”, can’t see any bolts inside the hull/keel

 

[stephen_h]

We have timber shoes on the keels of our catamaran.
Stuck on with CT1 or similar. No need for fixings / leaks!
I did also put some fiberglass tape at the ends to make sure they stay if the glue gives up.

 

[Tremyporth]

Looking to replace the wooden keel/shoe on my Mitchell MK1, anyone have any experience in doing this?
What sort of wood? possible with engine in situ? fixings?

Thanks for any advice

Hi Sea Limpet. I had to replace fastenings at the rear end of the keel on a MItchel 31 like yours. Grounding on a drying mooring over several years in a west-facing estuary seemed to result in 4 tons of boat hammering the rearmost fastening bolts to such an extent that one loosened and wore an oval leaky hole in the GRP hull moulding. The rear part of the wooden keel then began to separate from the moulding. You will have noticed that the keel on these boats has a pronounced draw downwards towards the stern, so it is the rear end of the keel that hits the bottom first, and in any waves, there will be a twisting motion on the keel as well as vertical pressure when it strikes the bottom. In view of that, I doubt if CT1 would keep things together in a heavy boat like this for very long. The wood keel is fastened onto the GRP keel trough in the hull moulding by galvanised nuts and bolts. The bolts I found were about 3 or 4 inches long and 10mm diameter. On the inside they are glassed over, so you cannot see them until you cut the glass away. On the outside, or bottom of the keel a hole saw or auger appeared to have been used to form a recess in which the nuts sit, surrounded by a plug of sikaflex or similar. This seemed to be very effective in preventing any significant corrosion. Several of the bolts are underneath the engine and gearbox, so you cannot do the job properly without removing the engine and 'box. As for the type of wood, well, whatever hardwood you can get. You may be able to re-use part of what is there. If you live in a rural area, you may have small local sawmills nearby where you could source native hardwood such as oak. You'll also want to replace the metal shoe to protect the wood from abrasion. Using several short lengths rather than a single long one means that in future you can replace them one at a time, moving supporting chocks as necessary with jack and wedges. Much cheaper than a crane.

 

[SeaLimpet]

Thanks for your replies.
Tremyporth, appreciate your detailed reply and can now tool up accordingly & yes, it’s the aft section that’s split after 46 years of grounding twice a day! Will make plans for the end of this season.

 

[tillergirl]

Can we have a picture of the wear and tear?

 

[SeaLimpet]

Can we have a picture of the wear and tear?

Painful to look at! I’ve temporarily made good the keelband & only ground on thick mud mooring.

 

[Rappey]

Would a strip of hdpe be a good solution instead of wood as its used in many high friction/impact areas like pile guides and dock sides

 

[tillergirl]

Well that's interesting. Here's mine below. I always thought it was a previous owner's addition of the 'shoe'. Obviously not. I was fortunate to refasten the shoe by simple screwing into the wood.

I take the view that the wood and 'shoe' is protection, not structural. That's good. Image 1 is the bad news. I was thinking if you could clean the damaged area so it is smooth, then glue and screw or bolt a graving piece to replace what has gone. However, the end has insufficient to 'meat' left. So: First the wooden keel is largely fine so leave the majority alone. Then aft, a piece needs to be scarfed to replace the damage, retaining as much as possible. Glue, obviously but it would need fastening as well. Access aft is going to be difficult; that will be under the engine and this is where I am stuck thinking how the scarf can be fastened vertically. I think the forward part of the scarf perhaps could be screwed or bolted sideways but the last 12" certainly need a vertical bolt. Some metal support on each side of the scarf in addition to the replaced'shoe' would help.

 

[SeaLimpet]

Hi Tiller girl, thanks for your reply & pic. Think my shoe terminology was a little wrong, I’m referring to the wooden part of the keel that is loose, largely rotten & in need of replacement. Of course a new keelband will be fitted too.

 

[tillergirl]

No, I think it is my 'shoe' terminology is wrong, keelband is right. This winter I shall have a good look at the keelband: replacing the keelband is a much easier than the timber. Sea Dog is a Mk1 as well so is the same age but fortunately didn't dry out much if at all during her life. I have just been wondering just how far under the engine is the end of the timber. The transducer (side scan) is clear of the end of the gearbox. I am speculating whether the end of the scarf could be bolted through (quite long) at a angle so you could get access to fit a nut (and angled spacer). I have the float of the bilge pump under the gearbox and it is possible (but hardly convenient) to put a nut on there. But would need very careful judgement.

PS. Sorry about the chocolate teapot. I never fitted it!

 

[SeaLimpet]

Think it’s going to be engine out for sure, end of season job - meanwhile, can't see the problem whilst on board enjoying!
Couldn’t see bolt heads when fitted replacement engine.