Lee-board Sailboats

Are they practical for cruising salboat in the 35-45 foot range ?

 

Phil Bolger says yes.
Reuel Parker says no.

both designed good boats.

 

many dutch traditional sailboats use them and of course thames sailing barges do and they are 92 feet long , plus in the victorian era there were bigger ones called boomies (because they had gaff mains with booms instead of spritsails)well over the 100 foot mark.
so history says yes.

look at the latest generation of volvo ocean race boats, racing trimarans, open 6os they all use twin asymetric daggerboards to create lift.
er who dosent do it?

of course the conservative sailing public,

conservative boat buyers racing classes that ban it and production boatbuilders that dont want the expense and knoe that customers will be scared of by anything too unusual - even if its 10 times better,

eg look how long it took j boats to get a foothold in europe, race comittees deliberately avoided courses that favoured them, and peopl have bought them now because they have proved the point by being in the pub long before the rest of us have finished!

but still cruisers still sail 70s boats that roll downwind or cheap underballasted german production boats that have 3 reefs in in 25 knots

oh well , for my money they are great and if fitted with endplates could be used as beaching legs!
phil

 

They allow a clear cockpit in smaller boats and without the hassle of centerboard upkeep, and prevent leeway better because the angle is more vertical when heeled. The boat's hull is stronger if there's no slot in the middle of the backbone. I don't think enough has been done to develop them for modern designs. There's nothing wrong with using leeboards on fast boats, such as now use unballasted centerboards (the Daysailer II comes to mind). In fact they would outperform centerboard boats in many cases.
They have the inherent design capability to be adjusted for angle 9from vertical). It seems this alone is an argument for more experimentation.
But alas, the reasons for how modern boats are designed has little to do with optimum sailing qualities and more to do with marketing and racing considerations.

 

It's easy to see why the Dutch favored them...just look at a map of the North English channel...you can imagine northerly winds shooting down especially northwesters....often pinning them in against their shallow coastline and of course many were merchant ships often traveling parallel to the coasts north to Germany or south to France and then back.They look unwieldy but obviously get the job done and are simply just another kind of swing keel...easy enough to tie off out of the way and easy to work on when they break...

 

Perhaps it is the thought of having to change them at every change of tack that discourages their use. However, if performance is not a priority they can be left down. Compared to a centerboard or daggerboard boat they leave the cabin center uncluttered. They don't need to be external of course; although interior designers can be quite clever at hiding daggerboards, a pair of leeboard trunks can be less intrusive tucked away behind bunks, lockers and cupboards.

 

L. Francis Herreshoff liked them, with most of his later shoal designs having them. In fact, his last commission was a 40' round bilge, leeboard ketch. He knew the limitations and worked around the issues. The biggest issue is the limits they place on hull shape. This generally places them too far aft on a conventional shaped hull, for good efficiency, so you have to drag some beam forward to accommodate the boards. In larger sizes, they can be more then a pain in the butt, but in smaller craft very workable.

Terry leeboards hang on the outside of the hull. You may be thinking about the arrangement often seen on lake scows, bilge boards, which is twin cases, one on each side of the boat.

Daggerboards are great on small craft, but lose their appeal as the board size goes up. Centerboards can be housed completely under the sole of many boats and is a design feature I use often.

 

Paul: I was using the term for any twin board arrangement where only the lee one is lowered but as you say the correct term for the inboard arrangment is bilgeboard. I was under the impression that bilgeboards were always fixed. I may try a leeboard on Dace to compare with the daggerboard. With her considerable beam, if it is adequate on Dace it would be adequate on any sailboat; the only downside is having to change sides frequently on a long upwind passage.

Leeboards are regarded as crude by the buying public so commercial builders go for daggerboards and centerboards. They are all about practicality, with the hydrodynamic efficiency of a daggerboard, the flip-up safety of a pivoted centerboard in shoal waters, without the complexity of either.

Sailing canoes often use a neat and simple arrangement consisting of a single tethered board that is held in place against the side of the hull by water pressure. A single, one-sided leeboard works fine too, especially on a narrowish boat. I've tried it on a canoe; it needs a solid pivot if it is to work on the weather side.

 

run ropes/cables between the bilge boards to balance each other

may make it easier to raise and lower just the one you want in the water

you could operate them from the cockpit

 

Traditionally leeboards only seem to have been used in areas where there was lots of shoal water and a need for flat bottomed boats: very specific circumstances. Otherwise they were avoided. Modern designers avoid them even more determinedly,and there are lots of good reasons why they are not very efficient. Traditional and modern wisdom seems nicely aligned.

That being the case leeboards are probably only really a good choice for a flat bottomed craft to be used in very shoal water...

 

You also need a rather flat area with tumblehome on the sides.

 

Gonzo: good point.

G4: not sure I agree with you on leeboard inefficiency. Considering the first thing a sailboat does when the wind hits the sail is heel, a leeboard coupled with a spot of Gonzo's tumblehome might actually be more efficient than a daggerboard, also the drag at the hull/board interface is absent. With twin boards an asymmetrical profile can be used for even greater efficiency.

Certainly they are inappropriate on a high freeboard, rounded hull with flare continued all the way to the sheerline, but there are lots of hulls that they would work OK with.

I think the small number of leeboards is far more to do with appearance than performance. They are not getting the attention they deserve from today's designers.

I've noticed the same obsession with symmetry; I used to sail a kayak with a Bruce foil on a single outrigger and a sail mounted on the gunnel and canted back toward the centerline. There were good reasons why it was like that and it worked, but it seemed to embarrass the big-boat folk at the marina.

 

I used to sail a kayak with a single leeboard (windboard on the other tack) and it worked fine.

 

Aside from matters of appearance the most often heard rap is that leeboards are surface piercing devices that suffer from ventilation. Whereas an inboard arrangement such as a dagger, centerboard, or bilgeboard has an endplate in the form of the hull itself. I have lonmg been curious to know whether ventilation is more debilitating than the turbulence and confusion that must surely occur at the intersection of board and hull. Unless an inboard type has a very well fitted case, then there is always some boiling within the case. Sometimes it will even spit.

On the other hand, there can be some nasty interference between the hull and a leeboard. In some cases the leeboard will be running inside a bow wave. There must be some turbulence generated between the two bodies, board and hull, in some manner or another.

Lee boards have a lot going for them when you missed the guess you made for finding the right distance between mast and board. With leeboards you just move them. With centerboards you have a more interesting and expensive problem.

Using Bolgers rope attachment method for lee boards you can just ignore the boards and they almost tend themselves. I sailed a Bolger Black Skimmer for a few days and the leeboards were rope attached. Amazing simplicity and there was very little muscle required to tweak them.

 

Messabout: the ventilation problem also applies to foilers where the main foil strut acts as a leeboard, but without the hull interaction. With a lightly loaded, hard-sailed flat-bottomed skiff it's probably not difficult to heel the boat enough to expose the bottom of the centerboard trunk.

I'm not sure what effect the bow wave would have on a leeboard. Could be good or bad. For efficient operation the hull design would need to be tweaked to minimize the disadvantage or capitalize on the gain as the case may be. Alternatively the leeboard could be mounted further outboard. That might be ugly, but you can get used to anything if you are sailing it and your competitor is looking at the stern ...