How to reduce slamming

Get a contessa32! My boat doesn't slam at all- such a pleasure !

I used to wince all the time with precious boats slamming upwind (pogo2, F28r trimaran, beneteau 27.7).

I wondered if heeling more might reduce slamming with some boats - reducing hull impact but probably a rubbish theory ?!
 
paulburn said:
Get a contessa32! I wondered if heeling more might reduce slamming with some boats - reducing hull impact but probably a rubbish theory ?!
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I think it does because the flat area due to heeling becomes more round (you know due to the sides of the hull). I say this because my boat which slams quite a long if motor sailing (and I absolutely hate it; yes I mentioned this again) it does not so if sailing at an angle.
 
Those who say they sail at 27 degrees off the wind are just being silly. People say silly things but we don't have to take them seriously now do we.
 
It is a known issue with fin keel yachts that tend to have a U shaped hull rather than V shaped, which is more or less flat in front of the keel, depending on the specific design. This gives greater performance at the expense of slamming. The only way to avoid it is to sail at an angle to the wave (which is very likely under sail). If motoring, avoid sailing against the wind, especially with seas higher than F5. The hull flexes and twists and in the long run it can cause gelcoat delamination, or the dislodgement of the internal fittings. In > F7 motoring against the wind can cause damage if the yacht falls suddenly in the through of the waves.

Newly designed yachts with thinner hulls might show problems earlier than yachts built before 2005 when there were higher margins left.

Fiberglass is quite flexible, but there is point where the resin eventually cracks and only the fibre then keeps the panels together reducing dramatically structural integrity.
 
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haydude said:
It is a known issue with fin keel yachts that tend to have a U shaped hull rather than V shaped, which is more or less flat in front of the keel, depending on the specific design. This gives greater performance at the expense of slamming. The only way to avoid it is to sail at an angle to the wave (which is very likely under sail). If motoring, avoid sailing against the wind, especially with seas higher than F5. The hull flexes and twists and in the long run it can cause gelcoat delamination, or the dislodgement of the internal fittings. In > F7 motoring against the wind can cause damage if the yacht falls suddenly in the through of the waves.

Fiberglass is quite flexible, but there is point where the resin eventually cracks and only the fibre then keeps the panels together reducing dramatically structural integrity.
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Right. That's it. I'm sticking to F3 or less.
 
paulburn said:
Get a contessa32! My boat doesn't slam at all- such a pleasure !

I used to wince all the time with precious boats slamming upwind (pogo2, F28r trimaran, beneteau 27.7).

I wondered if heeling more might reduce slamming with some boats - reducing hull impact but probably a rubbish theory ?!
Click to expand...

That is because your Contessa is a traditional long keel with a V shaped hull. Perfect for high seas, if only it were bigger :-) You are right it will be hard to make such boat slam.

And no, heeling more does not reduce slamming. On the contrary it could make it worse because the thinner freeboard would be banging the water in that case. It is the angle to the wave that does.
 
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paulburn said:
Get a contessa32! My boat doesn't slam at all- such a pleasure !

I used to wince all the time with precious boats slamming upwind (pogo2, F28r trimaran, beneteau 27.7).

I wondered if heeling more might reduce slamming with some boats - reducing hull impact but probably a rubbish theory ?!
Click to expand...

A Contessa 32 is the ultimate no-slam boat, you'd have to work hard just to make it slam! The trouble is it makes huge design sacrifices in order to gain that attribute. It's tiny inside for a 28 footer never mind a 32 footer. It's slow; wet; dark inside; and puts the loo in the gap between the saloon and the forecabin, which was a design feature ditched by humanity soon after we realised that we're not animals. But it's gorgeous to look at, doesn't slam and tracks very nicely.
 
Colvic Watson said:
A Contessa 32 is the ultimate no-slam boat, you'd have to work hard just to make it slam! The trouble is it makes huge design sacrifices in order to gain that attribute. It's tiny inside for a 28 footer never mind a 32 footer. It's slow; wet; dark inside; and puts the loo in the gap between the saloon and the forecabin, which was a design feature ditched by humanity soon after we realised that we're not animals. But it's gorgeous to look at, doesn't slam and tracks very nicely.
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Very true. I'm completely in love with it, emotionally engaged in a way never had before with other boats !
 
Well, a Contessa 32 in slamming conditions is one of the wettest boats around. Then when you go down below to dry out it's all arses and elbows being small and cramped; hideous things when wet.
 
BlowingOldBoots said:
Well, a Contessa 32 in slamming conditions is one of the wettest boats around. Then when you go down below to dry out it's all arses and elbows being small and cramped; hideous things when wet.
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Is there a sub 33 footer you'd rather be in in challenging upwind conditions offshore ?!
 
paulburn said:
Is there a sub 33 footer you'd rather be in in challenging upwind conditions offshore ?!
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Yes. Boats less than 33 foot that I have sailed in heavy weather: Rival 32, Sigma 28 and 33, Colvic 28, Moodys new and old, Wharram Phai. All boats that sailed well.

The Contessa 32 is a nice boat to sail, of that there is no doubt, but it is not a nice boat for living on if sailing in heavy weather. I had one for a week in the Firth of Clyde, end of season, mostly F5 to 6 (7) and it was not a pleasant week. I have done the same on the yachts mentioned and they were far more enjoyable.
 
Our 33 ft deep fin and spade rudder used to slam a lot when beating, so we reefed or motor sailed, still slammed. Now we shake out the reef, turn off the Volvo, drive hard with the boat heeled enough to make the companionway a challenge and the slamming stops, boat slices purposefully to your destination. Is this common to most AWBs or is it the Rob Humphreys design?
 
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johnphilip said:
Our 33 ft deep fin and spade rudder used to slam a lot when beating, so we reefed or motor sailed, still slammed. Now we shake out the reef, turn off the Volvo, drive hard with the boat heeled enough to make the companionway a challenge and the slamming stops, boat slices purposefully to your destination. Is this common to most AWBs or is it the Humphreys design?
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This is similar to what I said in post 23. I get the same symptoms! And I believe it's because you no longer sail with a flat area in front of the keel hitting the water and causing the slamming. Since the boat heals the area touching/hitting the water now has a better angle to do so. My theory for explaining it can be wrong but the practice shows that, for whatever reason, it reduces slamming.
 
cmedsailor said:
This is similar to what I said in post 23. I get the same symptoms! And I believe it's because you no longer sail with a flat area in front of the keel hitting the water and causing the slamming. Since the boat heals the area touching/hitting the water now has a better angle to do so. My theory for explaining it can be wrong but the practice shows that, for whatever reason, it reduces slamming.
Click to expand...

Yes I had read your post and would have posted as a reply to it, but as yours was already a reply the point could have been a bit lost.
 
cmedsailor said:
... My theory for explaining it can be wrong but the practice shows that, for whatever reason, it reduces slamming.
Click to expand...

There is another factor which may help to account for this. The more heeled the boat the more the rudder turned to bear away to go down the back of a wave acts, during the turn, to lift the stern and push down the bow. It is how Laser sailors cope with sailing through chop and I'd assume it has some influence scaled up to a keel boat.
 
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