Re: Wide stub keel

[Sayla]

Hi all,
I wanted to see if anyone had experience with wide stub keels - sailing, beaching mooring,.. general stuff. I noted a comment on the William & John Atkin website: "I have attempted to solve the headroom problem in a small boat by combining the excellent underwater form of the Sea Bright skiff.." ie a wide stub keel.

Anyway I've been doing a design for a trailerable (just) cutter with standing headroom, achieved the same - by making the stub keel wide. Width of bottom of keel 0.42m (16.5"), internal floor width approx 0.5m (1' 8") plus the angled internal hull both sides (3' between seats) - draft min 0.7m (2' 3.5").

Other specs if needed are... Lod 8.1m (26.5') , Lwl 6.77m (22.2' ), Loa 10.7m (33') , Beam 2.43m (8') , Displ light 2500kg (5500lb) , Pris.C. 0.55 with Design displ 2990kg (6590lb) , D/L 268 , Seat headroom 0.91 (36") , Standing headroom mid floor 1.82 (6') , ballast ratio approx 35%, simple static stability calcs appear to come out about 140 deg (preliminary), centreboard through lead ballast keel - the counterstern allows for a slightly bigger cockpit without the extra displacement of increased Lwl.
And here's a bit of a picture..



Thanks for any comments

Sayla

[JimConlin]

Consider wetted surface. It's more of an issue in a sailboat than a powered skiff.
If the SA/WS ratio is below 2, in light conditions, you'll get good with light sails or you'll motor a lot.

Consider the structure, particularly the load paths joining rig and ballast.

[Thorne]

Do you mean a box keel?

Some modern versions of the Sea Bright may have a keel like you describe, but certainly not all -- and the traditional Sea Bright / Jersey design certainly not (a surf boat of sorts).
http://www.folkstreams.net/film,41



The Gerr Marine design seems to have what you are describing - a motorboat design.

[Antti Alfthan]

Well...
the cabin room looks ok on paper, but you haven't the centerboard box drawn there; you'd have some 15 cm to walk on, each side, instead of 40 cm on the keel stub. And you are likely to have wet feet, there is no bilge. Like something was cut off from a displacement boat. I'd either choose a true displacement hull or a surfing one (with plenty of sail).

Instead of one centerboard you could have two, hidden under the berths, in the angle as shown, forgetting free standing headroom for speed and surfing - or this could be a keelboat. I love the gaff and topsail - why not rig a yawl? You have room in the aft for the mizzen. And taking the main mast a wee bit forward would give you a little more cabin room (and less foredeck)

[Tom Lathrop]

Sailed an S2 26footer with a wide and long keel that offered full headroom by walking in the keel. Probably the worse sailing boat I ever sailed. I owned an S2 Grand Slam 7.9M which is only one inch shorter but just the opposite in sailing qualities. Sailed one other wide keel boat that was almost as bad as the S2 26 but don't remember the brand. Island Packet 26 is better than those but still a poor sailer. Would not touch one for myself and only reluctantly get on one owned by others.

[Sayla]

Thanks for the input,

you'd have some 15 cm to walk on, each side, instead of 40 cm on the keel stub. And you are likely to have wet feet, there is no bilge

There's about 20cm per side at the table but that's ok at the table, walk through isn't really part of the design - simply the ability to stand around at the galley area. There is a shallow bilge, but it should be dry - strip and cold-mold construction - plus bulkhead floor load transfers.

Sailed an S2 26footer with a wide and long keel that offered full headroom by walking in the keel...........................Island Packet 26 is better than those but still a poor sailer. Would not touch one for myself and only reluctantly get on one owned by others.

So - I take it sailing quality is risky to be compromised - does the Island Packet 26 have a centreboard ?

[alkorn]

William Atkin's Topsy has just the kind of keel you're talking about:


According to the Atkin site, Blaine Bey of Victoria, BC, has a Topsy (Pacific Integrity) that he bought from the Center for Wooden Boats in 2006:


Perhaps you could contact Blaine and ask about his boat's sailing qualities. I'd be really interested to find out, myself.

[skaraborgcraft]

i would be interested myself in any feedback on this issue. Im currently looking into the Atkins "two brothers", unfortunately not in the design catolouge,but in an issue of motor boating. It has the same keel layout, and is supposed to get 11mph on 12 hp.

Im still doing paper studies to see if this is realistic. Cheers