New 14'-16' Daysailer/Weekender Design: Raison d'etre

[Doug Lord]

I've been very interested in the Mini 6.5 designed by David Raison-it just won the Mini Transat. To say that it is unique is quite the understatement. To look at it and think it would be fast- before you knew- would have been very ,very unlikely. Yet this incredible design has opened up a whole new avenue of design-one which could bring innovative thinking to very small boats that would never, ever, even have been considered until now.
I've done some doodling with ideas between 14' and 16' using the basic princibles of Raisons design, as I understand them, and one thing stands out: for daysilers in this range there is now a way to get an incredible amount of room in a small boat, that until now, many would have thought ridiculous.
I'd like to suggest that anybody with the imagination and interest take a shot at some rough sketches and give some thought to how the "license to deviate" just granted by David Raison could inspire trully new small sailboats that can perform well with unheard of accomodation. The key will be not to overdo it in terms of weight.
I'm interested in ideas on developing this concept, based on the midwest racing scow shape, and David Raisons taking of that concept to a level of performance and interior space never seen before. My thinking is that, in this time of disatrous economic times, maybe we can take Raisons innovation one step smaller and create small boats like none that have been seen before. Remember: anybody can make a big, wide flat barge- but the crux of this challenge is to use the room the concept offers yet have the boat perform exceptionally well!
It seems to me that this is an exciting challenge with tremendous potential based on Davids inspired design.
I'm going to take some time off everything tomorrow and do a rough sketch---and that will be it for me for a long time! Maybe it will inspire some of you to join a discussion about this complete with your own rough(or not so rough) sketches.

For those who haven't seen it yet, David Raison's Transat winning design:
click on image:

[sharpii2]

Hi, Doug.

There are a number of designs out there already.

The oldest of the lot are the 'Pelican' series ('12' and '16'). Though boxier looking, they have many of the performance attributes, including frequent planing.

Also, in pdracer land, there is the 'pdcruiser' and the 'pdgoose'. the 'pdcruiser' is a pdracer stretched from its 8 ft length to 10 ft. The 'pdgoose' is a pdracer stretched to 12 ft.

Mike Storer has built a 'pdgoose' and has found it quite fast.

Along with scow and pram advantages come disadvantages. The primary one being slamming into head seas with a squared off bow.

If the boat is built low to the water, its leeward corner can go under, inviting a huge amount of water on the deck. The 10 ft scow I had (my first boat) did that, lifting a 20 lb navy anchor I had stored on the bow and gently setting it in my lap.

If the boat is built higher, the squared off bow will slam into head seas, creating a huge fountain of spray to douse everyone on deck.

PDracer's have been used in the 'Texas 200' raid with success. That is primarily because that event is mostly down wind. These boats can sail upwind surprisingly well, if the water is relatively flat and it has a proper leeway preventer. But with head seas, it is a totally different matter.

[Doug Lord]

Sharpii- as best I can tell there is no boat currently on the market that has the combination of room and performance that David Raison put together for its size in the 14-16' range.
Heres a rough sketch of an idea - would be designed to be sailed at about a 15-20 degree angle of heel:
LOA 16'
Beam 8.25'
Tunnel hull
weight est:
-- with 150 lb ballast in keel- 470lb
-- w/o ballast- 320lb
Displ. with 320lb crew=:
-- with ballast-790lb.
-- w/o ballast-640lb.
SA- 200 sq.ft + asy spin-with "performance" mods like racks- more SA....
4' X 6.5' bunk forward
sitting headroom inside



Pictures-1&2-rough sketch of concept/ numbers above based on this, 3&4 RC scow with similar shape-

click on image-

[Doug Lord]

Here are some of the boats you mentioned :
Pelican-the 16 is 8' wide with 187 sq.ft of sail-Weight 950lb.. http://www.platypusboats.com/pelicans.html
--
PD racer-http://www.pdracer.com/

click on image: Left=PD racer, Right=Great Pelican

[sharpii2]

Originally Posted by Doug Lord

Sharpii- as best I can tell there is no boat currently on the market that has the combination of room and performance that David Raison put together for its size in the 14-16' range.
Heres a rough sketch of an idea - would be designed to be sailed at about a 15-20 degree angle of heel:
LOA 16'
Beam 8.25'
Tunnel hull
weight est:
-- with 150 lb ballast in keel- 470lb
-- w/o ballast- 320lb
Displ. with 320lb crew=:
-- with ballast-790lb.
-- w/o ballast-640lb.
SA- 200 sq.ft + asy spin-with "performance" mods like racks- more SA....
4' X 6.5' bunk forward
sitting headroom inside



Pictures-1&2-rough sketch of concept/ numbers above based on this, 3&4 RC scow with similar shape-

click on image-

Interesting design.

With all the bubbles and bulges, it looks like something the Soviets might design.

In strong winds, it would be faster than an ordinary scow. In light winds, it might be slower.

The hollowed middle actually adds whetted surface area. It also subtracts from interior volume, forcing you to go higher to get adequate headroom in the cabin.

It would make an excellent GRP boat. All those compound curves add strength without adding weight.

A scow holds one trait similar to a multihull. Its heeled waterline to leeward gets flatter and straighter, as the boat heels. With a multihull, it is always quite straight. The buoyancy shifts further to leeward for this reason. Hollowing the center adds to this effect.

Technically, it is still a mono hull, because it still has just one water plane.

I can imagine, in some situations, the hollow part in the center may pound and slam terribly, just like an over loaded catamaran with a low wing deck.

I've often considered scows to be working class sailboats. According to Howard Chapelle, they were once as common as Chevys. In the days of working sail, one built the least expensive boat that could get the job done. Since most of the work was coastal and even inland, the scow hull form was quite well suited.

So far, I have completed just two boat designs. Both of them are scows. They are both straight sided and quite narrow. They have a deep rocker to their bottoms and have very small transoms. Level, they have short waterlines. But when heeled, the waterline extends, just as the lee part of it gets flatter. I imagine, they will be quite fast for non planing mono hulls that can carry a decent amount of weight. They will heel as much as 20 degrees and, hopefully, present a 'V' bottom to any chop, just like a sharpie.

I entered one of these designs in a WOODENBOAT magazine design contest which was supposed to be for a racing boat for small children, 5 to 7 yo, IIRC, that could easily be built by them with supervision from their adult caretakers. It was also supposed to be usable when they grew up.

That contest turned into a disaster. The winning boat got built, but proved to be quite unstable, especially when swamped. It preferred to float upside down in that condition.

My design did not even get mentioned. Now that I look at it, I can see why. A rudder was tacked on to the aft transom, which was quite shallow and cleared the water by a noticeable distance. I imagine they didn't like it. Now, when I look at it, I don't either. I should have cut the hull a little further forward and gave myself a deeper transom and a slightly shorter boat.

The 32 sf sail plan I drew for the adult version, should have been for the children's version and the adult version should have had a rig almost double that size.

Other than that, I believe it met all the requirements for this contest, including being self rescue-able by its pint sized crew, without outside help.

The second boat I designed was based on that one, but was larger, 12 ft, instead of 10 ft, and had a different deck design. Other than that, it was the same boat. (see attachment)

I have been thinking about shortening the hull by about 9 inches, so I have less hull structure and a better supported rudder that doesn't look quite as dorky.

I've had visions of sailing it in a 'raid' race. It has just enough displacement and is just long enough to allow sleeping aboard.

[Doug Lord]

Originally Posted by sharpii2

Interesting design.

With all the bubbles and bulges, it looks like something the Soviets might design.In strong winds, it would be faster than an ordinary scow. In light winds, it might be slower.

.

==================
Thats an interesting take!
I tried to use the basic Raison concept in a much smaller boat just to see what might be possible. The curves are simply to allow the boat to be lighter than it would otherwise-it is not a "homebuilt"-strictly a "production" concept.
The performance of the M20(tunnel hulled scow) suffers in very light air but is generally a good performer. This thing has a much wider L/B then does a "normal" scow, as does Raisons boat. For a 16' daysailer it has unmatched interior space and a giant cockpit. It is designed for two people max-more and it would be a dog in anything under 15 knots....
Why don't you do a sketch of something in the 14-16' range that could be called a "daysailer-weekender" either homebuilt or production using what you understand are the innovative and successful parts of David Raisons design? It would be great to see your thinking on the subject......

[Doug Lord]

Well, I've thought a lot more about this concept and it seems to me that it has real potential in terms of a roomy, performance daysailer in relatively flat water-like the water in so much of the country-and for hundreds of miles around me. The cabin could be reduced-there are a lot of mods that could improve the boat for certain "niche" applications. There is no daysailer that I have seen including my own 18' footer the TS-18(80 boats sold) that has the combination of room and potential performance of this concept. I think boats that use some of the concepts proven by David Raision have a lot of potential in this area of sailing.
This concept really calls for about a 48" proof of concept RC model............

click on image: Note that the two views of the concept boat are at different scales for clarity. It's important to remember that the boat would be designed as a scow and would therefore be designed to sail at an angle of heel. It utilizes a tunnel hull as does the Melges 20 and a few other pioneering lake scows because the wetted surface of the boat is reduced quicker as the boat heels while still retaining a flat planing surface aft. The rig would be designed to prevent the boat from turtling and a canting mast system might be able to be used to assist in righting the boat.

[rapscallion]

Yes! I like it too! I love Sailboats that look like stealth spaceships!