Can I dry out with a prone skeg (Sadler 34 extra shallow keel)

[maej]

Sorry, another stupid question from me.

I need to dry out briefly to measure my prop taper etc for ordering a new one, then again in a few weeks to fit the new one and probably again to renew the antifoul. I have access to a concrete slipway with a wall alongside which I could lean against to dry out.

What worries me is the slipway is slightly concave in places, and as my skeg is as deep as the keel the boat could end up resting on the skeg and front edge of the keel. I'm no expert but the skeg does't look like a particularly heavy structure to me so I don't know if it can handle 6 tonnes of boat resting on it, especially if buffeted by any wash before the tide is out. The keel is about 12 foot long as well so the forward end is well forward of the center of gravity.

Any advice, reassurances or warnings?

Below are some pictures of my boat showing the keel, skeg and rudder.

I had thought about trying to put something under the aft end of the keel to try to give me a few degrees nose down thus lifting the skeg, but not sure how to do that safely, and as the keel tapers to 1/2 inch at the back it would probably slice through anything I can put there.

 

[jwilson]

Did not know that Sadler built anything with that long and shallow a keel - was she a one-off or modified after build?

I agree I'd not like to have her resting on forward edge of keel plus skeg. Someone in wetsuit with bit of 2x6 timber maybe, or a 2" plank with a couple of sash weights at the ends, suspended from the deck on either side?

 

[Tranona]

Unless there is something very unusual about your shaft then it should have a standard taper depending on whether it is metric or imperial. Although some Westerlys were made with odd tapers, don't think Sadlers were. You might check with Martin Sadler before going to the bother of drying out. Provided the surface is level would think with that long keel base it would dry out quite safely

 

[maej]

Did not know that Sadler built anything with that long and shallow a keel - was she a one-off or modified after build?

It surprised me when I first saw her during the survey lift, I was expecting the standard shallow keel. I think it is a one off, in the huge pile of papers from the previous (original) owner who I never met, it looks like he spec'ed it like this but also with reinforcement for beaching legs, though I see no evidence of reinforcement on the beam and certainly no sockets or connections for legs so I guess he dropped that idea. My best guess is that it is a lift keel stub without the void for the plate, but having never seen a lift keel Sadler 34 I can't be sure.

I don't like the idea of anyone being near the keel at the point she is settling on the bottom, too much risk of body parts getting crushed, but I like the idea about the plank and weights. If I get a sturdy fence post, suspend it at each end and weight it with a couple of dumbell weights and maneuver it under the aft of the keel hopefully that would work. I wonder how much weight is needed to sink a fence post.

 

[maej]

Unless there is something very unusual about your shaft then it should have a standard taper depending on whether it is metric or imperial. Although some Westerlys were made with odd tapers, don't think Sadlers were. You might check with Martin Sadler before going to the bother of drying out. Provided the surface is level would think with that long keel base it would dry out quite safely

I think the standard Sadler 34 fit was a 1" shaft with 1:12 taper and 0.25" key way with a 16" dia 11 or 12 pitch fixed 2 blade prop. Mine has a 15.5" dia 12 pitch fixed 2 blade prop. I suspect the shaft will be standard, but the not quite standard prop gives me a little doubt, and it's a lot of money down the drain if I order the wrong dimensions for my new prop.

If the slipway was really level I wouldn't worry, but in a few places the angle of the slope lessens a little creating a slightly concave slope.

Frustratingly I did once measure the shaft, but I can't find the paper now.

 

[vyv_cox]

Assuming that the keel is made of metal (cast iron or lead?) it is not going to break when you dry it. The critical point is the strength of the hull and the number of bolts holding the keel on. Deep keel and shallow fin Sadlers dry out regularly, so the hull strength is not really an issue unless your keel has been attached in a very unusual way.

So far as your slipway is concerned you need to take the usual precautions, i.e. level and uniformly hard. If the one you have in mind is not suitable then try elsewhere, it isn't difficult to find somewhere in most locations. Failing anything else most yards will lift you for an hour in the slings and put you back.

If you look at the photo of my 34 on the home page of my website you will see that it is dried with quite a lot of weight on the skeg. This often happens and seems to do no harm.

 

[JumbleDuck]

I'm no expert but the skeg does't look like a particularly heavy structure to me so I don't know if it can handle 6 tonnes of boat resting on it, especially if buffeted by any wash before the tide is out. The keel is about 12 foot long as well so the forward end is well forward of the center of gravity.

The skeg wouldn't have to take anything like six tons, because it is a lot further from the centre of gravity than the forward end of the keel. It looks to me as if, roughly, the forward edge of the keel is about 4' ahead of the cog and the skeg is about 16' behind the cog. Those lever arms are in the ration 1:4 so the share of the load taken would be in the ratio 4:1. That would mean about 4.8 tons on the keel and 1.2 tons in the skeg.

Hmm. I think I'd want to take the load on the keel if at all possible. Baulks of timber weighted down on the slip at the previous tide?

 

[West Coast]

If you are concerned, why not, during a previous low tide, position some packing material under the region where the keel will land, so as to create extra clearance for the skeg? Make careful note of their position so you can set the boat at the correct location at high tide.

As I type, thinking of what material to use for the packing - perhaps some steel beams, set transversely to the keel? Some lumps of thermoplastic material would be ideal, but with a density of around 1, you would need to weight them somehow at the ends to stop them moving as the tide comes in.

 

[Bav34]

My boat sank back slowly onto its rudder as in this picture, and there was a small amount of groaning as the vertical spade rudder was subjected the the load, but we stayed there for three days as I wasn't concerned:

Here we dried out more successfully ... again, stress free:

On both occasions there was little chance of wash.

 

[Tranona]

I think the standard Sadler 34 fit was a 1" shaft with 1:12 taper and 0.25" key way with a 16" dia 11 or 12 pitch fixed 2 blade prop. Mine has a 15.5" dia 12 pitch fixed 2 blade prop. I suspect the shaft will be standard, but the not quite standard prop gives me a little doubt, and it's a lot of money down the drain if I order the wrong dimensions for my new prop.

If the slipway was really level I wouldn't worry, but in a few places the angle of the slope lessens a little creating a slightly concave slope.

Frustratingly I did once measure the shaft, but I can't find the paper now.

The taper and keyway will be the same 1:12 irrespective of the diameter of the prop. Shafts are made to standard size and prop hubs machined to suit. The prop is probably a 16" originally cut down to 15.5" to achieve much the same as a 16*11.

 

[maej]

The taper and keyway will be the same 1:12 irrespective of the diameter of the prop...

What I meant was if the prop wasn't the Sadler standard fit (but looked old enough to be original), then the shaft may not have been the Sadler standard fit either. My boat was partially fitted out by the original owner.

Is 1:12 the general standard taper for a 1" shaft or are there other standard tapers?

 

[alahol2]

If it were a 25mm shaft then the taper is more likely to be 10:1. I've never heard of anything other than 12:1 on imperial and 10:1 on metric sizes, but who would guarantee it?

 

[Tranona]

Agree. If it is a 1" shaft it will be 12:1 - unless the perverse original owner/builder had an existing prop machined 10:1 and machined the imperial shaft to fit - highly unlikely!