Easy way to reduce rolling on bilge-keeler?

There is no "1990s Beneteau 31.7" that reduced freeboard compared to a 1980 Beneteau 30. This did not exist. The facts are simple and clear.

Yes, the 31.7's hull shape is different to earlier boats but that is irrelevant to your claim which was "the second position went to 80s IOR yachts probably because the high freeboard and cabin height compared to length and beam". Work out the comparative freeboard and cabin height compared to beam and length of such yachts and it is clear that you are wrong.

Your claims about your personal experience can be ignored, because you have so often insulted so many people who have far more relevant personal experience than you have that it would be hypocritical to listen to yours. Instead of learning from people like Froude - whose work has been proven to be incredibly useful - you ignored it.If you wanted your own experience to be listened to then you should not have thrown around the vile insults you threw at so many other people about their experiences. Given the abuse you have thrown at others, it is ridiculously hypcritical for you to expect others to respect you or your experiences.

 

No i haven't insulted you and and you are hijacking the thread, i have designed almost all types of sailboats and you have no idea at all

 

Doodles are not designs. You are completely wrong when you claim I have "no idea at all" since I have a lot of experience (and a bunch of championship wins) in many areas of sailing.

I didn't say you insulted me - you have insulted many other people like the experienced engineer who you so arrogantly insulted here the other day, thousands of boat owners, and dozens of designers.

It is stupid of you to complain about my "hijacking" since my posts were direct and relevant responses to a claim you made. The science of rolling has been known since 1861 so your apocryphal evidence about rolling has been known to be worth little for over 160 years.

You have been warned yourself about hijacking threads with ridiculous and insulting posts about language and politics, so it is hypocritical for you to falsely complain that I have hijacked this thread.

About 10 days ago I passed a double-ended long-keel traditional wooden boat with low aspect rig at anchor. It was rolling like a pig compared to modern boats around it, as it has done in that bay on other occasions. The point is that science shows that while that old boat rolls in the wave period experienced a lot of the time in that bay, it may not roll in other places. It goes against basic and well proven science to say that because you sawa few boats of two sorts roll in one bay, such types are more prone to rolling.

 

Call me when you make a clubswan36 replica, it has a flat ultrawide beam with little lateral stern overhangs and pyramidal cross sectional shape from midship to bow, its a capsize risk but the hull is worthy to try to model and understand hull lines, this boat is similar than ceccarelli design Neoyachts sailboats



Full keelers roll too even if they have bigger displacement that makes them seaworthy in rough seas but also their vertical profile and big keel barrier that improves helm also will collide with passing waves and can create pendular momentum at anchor too, still not the biggest offenders

Don't forget to buy a hanse and regretel, I saw them at discount half life manual labour

 

I like the idea - hope you get to build it!

 

Some very useful tips there, thank you! I agree, the added weights on the bilge keels could be easily faired; that's something I can do myself. I would be reluctant to remove them altogether because apparently she had a tendency to broach before they were fitted.And the reefing tips are gold-dust! It seems as if I just need to adapt to the handling of a very different hull profile; thanks very much for your advice.

 

I have to use the word “Codswallop” more frequently; brilliant!

 

Thanks, that boat concept is a sort of old fashioned sharpie but using curved wood instead flat beams (same curve everywhere so no leftovers are created even with plywood) and rotating the freeboard frames to make a longitudinal transition like some yachts from bow to stern

I remember a shoal yacht design that used a similar triple fin approach but the design didn't have an author and disappeared from search engine results few years ago.

With few people, simple tools and recycled wood it can be built easily

 

Well this is embarrassing, at least you have a phantom webpage

 

Interesting:

Have you done any analysis of the design (form coefficients, weight study etc)?

 

I rather prefer to concentrate in hull shapes and real sailing scenarios, the boat has similar cross-sectional proportion to lifeboat designs, that was my intention from the begining, however the boat lacks cabin height buoyancy (lifeboats upright by cabin top buoyancy) and has too much stern beam to selfright after capsizing without any permanent ballast or ballasted keel-centreboard (only cargo stored in bilge abd water ballast) so I think it needs a stern arch float like used in RIBs, I think all sailboats should bring one to help uprighting mostly wide beam sailboats.


That square sharpie shape but with curved profiles has good form initial stability and doesn't slam much as total flat (also the tri-fin help reducing slamming) but that shape is a risk for wave capsizing like cargo ships with near square cross section hulls

This boat has a different weight approach like kite boats because the punctual loads are reduced and so weight reduction can also done with multiple frames and fabric on frame on some parts of the boat.

I did another version with the stern arch and 4-5 smaller masts to reduce the gap of mast load and bare hull structural reinforcement

Also the low height of the rig create different heeling so this boat needs to be built in 2m scale for example and test heeling in open water and choppy and beaches waves to test capsizing and uprighting behaviour

 

Here's more pictures of the hull with lines

 

You may find form coefficients are useful at least to provide some measure of comparison with other vessels you are emulating or are inspired by.

Is there a rudder?

 

In that design the bilge fin rear board is attached to a sort of skeg rudder, also the end of the central keel has a skeg rudder too to sail in shallow waters, maybe a sort of semi balanced skeg rudder

Also in shallow waters one or two wide leeboards could help

The bilge boards cannot be too deep because the heeling they create and lack of permanent ballast on keel, i thought of making asymmetric boards in first to improve upwind but this is a compromise of combined heeling with board depth and mast height and hull shape, so that's quite difficult to study but rather tested

The flat sharpies seem to bring good righting moment compared to the rest but thats also recipe for wave capsize so lateral midship overhangs are necessary like in Egret sharpie, so i could do that with this hull doing lateral overhang on midship or maybe a cold forming hull with transition curves to bring some curves and improve stability curve and lateral wave capsizing

 

Given that much of the keel is hidden in the shadow of both keels, its area to damp rolling is somewhat reduced. More keel is not always good, I sailed on a Colin Archer long keeler that would almost dip both rails when a wave swell would sweep through, yet on a narrow fin and rudder lightweight boat, there was nothing under the water for the wave energy to have much impact on.

I think your rolling is more to do with the hull shape rather than lack of keel area. I had the same trim issues swapping out an old Lister for a Yanmar. I purchased scarp lead pipes that i beat flat and laid them in a cement slurry.