High aspect lifting keel

I´m long therm thinking about creating versatile even ocassionaly trailerable yacht. I have experiences in boat building. I wanted to build the whole boat, but that is too timeconsuming. So therefore Im now inclined to buy an old Benettau First 29 DL and modyfy just the keel part.

I´m thinking about high aspect lifting keel to the effort make more sense to me.

To make high aspect keel, the keel must go above the deck when up. Or even above the boom.

I do not want to reinvent the wheel, so if you have any examples of such lifting keel design, please send it here. (I have seen one, but I canot find it now).

The idea is to create steel trunk and steel frame to distribute the loads on the hull. Upper part of the keel will be rectangular with sliding parts. For lifting using just ropes and pulleys. In the end possitions it will be fixed by bolts. Sailing only with the keel fully down. Boat will be mostly out of the water.

1. If the keel will go to the boom, the draft will be 2,5 m. Bulb about 700 - 800 kg.
   
   
2. Draft 3m. Bulb about 600 kg. Maybe easyier to lift. Lifting in two steps.
   

But how to raise it above the deck? What about kicking in place?

If someone has some Idea or experiences, please let me know.

 

Seems like the lifting keel version of the Beneatteau 29 is already trailerable. Not sure how much gain in petformance you expect to gain with your modification, at the expense of deeper draft which has it's limitations on cruising in more shoal waters. A nick name for them I have seen is Bendy Toys implying tbey are ligthy built production boats. Some one once replied to me when asked what kind of a sailboat do you have, replied it is just a Benetteau... Beneteau First 29 for sale £13,000 - Ullswater Holiday Park https://ullswaterholidaypark.co.uk/beneteau-first-29-for-sale/

 

I expect significant improvement of performance, especially upwind, since the position of weight will be about 1,5m lower than in DL version. Also better shape.
I sailed once some Feeling with ballast and was not happy about that...

It will be also possible to sail in shallow waters. Just only with the engine.

 

Examples: Balta Patrick Architecte naval, architecture navale, Motor yacht, yacht design, catamaran http://balta.fr/enfant%20perdu.html
Dudley Dix Yacht Design: Didi 950 Progress & Lifting Keel Option https://dudleydix.blogspot.com/2014/10/didi-950-progress-lifting-keel-option.html
Didi 950 with lifting keel https://www.flickr.com/photos/23039635@N03/24380538716/in/photostream/

You have to sift trough the photos, there are many details visible. Dix has several versions of trunk and keel arrangements buried in his site.

The easiest way is to have the trunk fixed to both hull and deck, this gives the strongest arrangement. Lifting either by rope and pulley attached to the mast or by a hydraulic cylinder. Fixing the keel in place up or down via transverse pin. The trunk can be rectangular with internal hdpe guides and inspection plate, or molded to the fin shape. The fin can be a steel fabrication or a wood core composite. You can have a bulb or you can have the tip of the fin made from lead (this way you can retract the foil completely trough the deck instead of having to lift the boat).

 

Um, no. Just don't. There is absolutely no reason to build a 3 m draft Benny 29. Even 2 m is a bit silly. It won't do anything the stock boat won't do except not be able to sail or moor in decently shallow water. You won't be able to see the bottom at 2 m. But you probably can at the stock 1.65 m. For a trailer sailer, it's all about time on the water, not speed. I'd be looking at 1.5 to 1.6 meters and keep it all inside for ease of storage and transport.

 

To philSweet - I disagree

I´m also thinking about modifying the hull little bit. Does anyone have hull lines data or anything to create 3D model? Or where to find that.

 

Sounds like you are you thinking in terms of a giant dagger board? Such a board, with a nice aero cross section shape will create some lift. Lift of such a foil, is a function of velocity. a long board will have much wetted surface area which will cause drag. It is uncertain how much the added drag will slow the boat.


You will only discover the result after all the work and expense that you have invested. A modification of that kind is a real crap shoot with the odds for failure too high to make he mod worthwhile

 

And why not a used First 27.7 QR , which already has a lifting keel ?

FIRST 27.7 BENETEAU FRANCE
untitled

 

First 27.7 is pretty good idea to make my life easiyer. But I think I will stick with First 29. It is suited more for family cruising and heavy weather. Mast is on deck. I somehow like the First 29 more. But I need to check First 27.7 in person for sure.

I browsed the DIDI design pages and some other boats. I like the way Didi build the keel fin(steel plate on round tubes) and the trunk. The steel plate of top of the keel is then bolted to the trunk to make more secured position.
I´m leaving the idea of rectangular upper part of the keel fin. I don´t no see need of that anymore. The HDPE slides in trunk can be positioned in the place of round tubes of the keel fin.
But I would like to put the keel fin from the top of the boat. Therefore the lead bulb must be demountable. It would be also big advantage for trailering the boat. I live in the middle of Europe and I want to sail both south and north part of Europe.

So the qeuestion now is - how is the lead part of the keel mounted to the keel fin? Are there some examples of demountable keel bulbs?

 

Conclusively not daggeboard! But fint with weighted bulb.
I have experience and people to fabricate such part from steel ...