Lifting keel banging Seal 28

[chriscallender]

I recently (June) purchased a Seal 28, and I'm delighted with my choice, having recently completed a channel crossing and having had a lot of fun over the summer.

However, there is one problem that I wondered if anyone has come across before? I posted this on the Seal Association web side but so far I have not had any replies there, so I'm also posting here to a wider audience for ideas.

When the lifting keel is in the down position and the boat rolls, a banging noise comes from the keel. In the sheltered waters of the Solent, this was not too noticeable, although I had heard happening it and I was intending to look into the problem over the winter. However, when crossing the channel with a relatively big following swell (1-2 metres?), the banging coming from the keel was very loud (both annoying and it sounded like it would be doing some damage to something). I had to lift the keel considerably (approx half way up) to stop the noise. Fortunately I was on a broad reach crossing the channel in both directions so I was able to do this.

I believe that the keel is moving laterally and in fact I once took the cover off and had a look into the keel box whilst underway. Its possible to see the keel moving by about 1mm from side to side which causes the banging.

In case it is relevant to the problem, the previous owner replaced the keel lifting wires last winter and I was wondering if these are not quite the correct length, so that the keel is not going down quite as far as it should and is "swinging" from side to side on the wires. Does anyone know if there is some kind of platform that top of the seal 28 lifting keel is meant to sit on when it is lowered all the way down?

Anyway, if anyone has any ideas then I'd be glad to hear about them. The boat will be lifted out on 28 October and I'm very keen to get this problem properly fixed for next season - if there is anyting that I need to try before the boat comes out to confirm the cause of the problem then I need to do it fairly soon.

Thanks for any help

Chris

 

[chriscallender]

I think I know the answer to this one now - the new keel wires are probably a bit on the short side. I'll check next time I'm down whether there is any slack in the wires when the keel is lowered completely.

Chris

 

[extravert]

I used to have a lifting keel boat (an Extravert). No keel banging on that, but the advice I received from the manufacturer was that the keel should always be fully down and secured when at sea, because otherwise in the event of a knockdown it may fall back into the keel case. This would mean that the boat would not right itself (the keel on an Extravert is its entire ballast). I don't know whether the keel on a Seal 28 is ballast or just a plate, but if it is ballast it may be safer to leave it down all the time.

 

[chriscallender]

That's an interesting point, and one that I found some discussion of on the Seal Association forums. The Seal 28 keel is definitely heavy enough (about 1000lbs from memory) that the consequences of it escaping in a knock down really don't bear thinking about. There is also about 2000lbs (?) in a fixed long stub keel, so the lifting keel is not the only ballast but heavy enough that I imagine it would make a big hole and sink the boat whilst inverted if it got loose (quite apart from the other dangers of 1000lbs of escaped ballast in heavy seas).

In the standard design it seems there is nothing to keep the lifting down apart from gravity. So I'd feel a lot more comfortable if I can come up with a modification that positively locks the keel down but is also easy/quick to unlock (I keep the boat on a semi-tidal mooring so the keel needs to be left up when I'm not around at least on big spring tides and anyway I don't want to loose the benefits of having a lifting keel). And also needs to be very strong.

Anyway your post has got me back to thinking about designing a locking mechanism again.

Chris

 

[charles_reed]

I had thejunior brother of the 28, the Seal 22, which had exactly the same keel assembly together with some additional bonded-in ballast.
I'm afraid your diagnosis is unnlikely to be correct.
The reason for the banging is wear on the two large Teflon blocks which run in the two bulges in the keel housing. When the keel is fully raised the bolts holding them in are accessible through two eccentrically placed holes and with a little dexterityyou can finagle the blocks out through the top. In my case I merely packed some 316 plate behind the blocks to ensure a tighter fit and it lasted the 5 seasons until I sold the boat.

The 22 was a grteat little boat and the 28 was the design from which Angis Primrose developed his 1st designs for the Moody range.

I was so sold on the lift-keel concept that I now have a Parker 31.

 

[chriscallender]

Hi Charles,

Thanks, that gives me something else to think about. I guess that at 22 years old there is every chance that these blocks are worn. Probably thats the 1mm gap that I could see when I looked into the keel box and watched it banging while under way. So over the winter I'll look into replacing the blocks or adding that 316 plate!

I agree that the Seal is a great design, and the combination of shallow draft and good sailing performance from the lifting keel takes some beating.

 

[PhatBuoy]

Sail aboard a Parker 335. Fantastic boat. Might be worth contacting Bill Parker for some advice. He will definitely know the best cure and does plenty of refurbishments on Seals.