Leeboards , Bilgeboards , Triple Keels - Reducing Excessive Heeling

[blueyama]

As a daysailer or racer it is fun to heel the rails into the water however Cruising as a life choice stability becomes a virtue.

This is where I was doing some research on the China/Dutch Leeboards, funny looking things, however they seem to make good sense. It retracts and functions much like a centerboard but instead is mounted to the leeward side of the boat. Its other pros seem to be reducing sideways drift, preventing or lessening leeway. I've seen Leeboards (including bilgeboards) on many small boats or very shoal drafted boats but not too many full keel boats (im interested to know of any). I'd image it would serve the same advantages. I'm curious to hear from anyone that may have had the joy of using leeboards (or bilgeboards)?

Leeboards lead me to Bilgeboards which are in affect fixed leeboards closer inward toward the center of the hull. Serving the same purpose. This in turn lead to the idea of adding bilgeboards to a shoal to medium draft boat 3'-5' (making it a Triple keeled boat) for a safer ocean going vessel. Could one do this with just any boat and would it truly make it a more seaworthy offshore boat? And the dark side: what disadvantages may arise from adding bilge boards?

Another cool advantage is for painting her bottom, a triple hulled boat on the hard would be a breeze, according to the photo.

[blueyama]

I need to make a correction. Bilge Boards are unballasted retracting boards so you couldn't use these to go on the hard but you could use Bilge Keels.
Bilge Keels are unballasted fixed boards. Let me hear your words of wisdom about either one?

Learned a new fact Bilge Keels act as roll dampers.

[Hudson Force]

Originally Posted by blueyama

.................. what disadvantages may arise from adding bilge boards?............................

Performance. Ok, it's true, - I don't have a "performance" boat, but that is the best answer.

[SimonV]

True bilge keels have been in use for hundreds of years, usually a small stumpy strake the length of the hull just below the water line. Bilge keels on sail boats are deeper and will allow the vessel to take to ground with a reduced draft, not as efficient as a centre keel but they do have there place. I can see issues with the strake type keels on a sailboat, it may slow the roll in an anchorge but would be a bugger on performance.

[Paul Elliott]

The downside is lots of additional wetted surface. If you want to reduce heeling and improve performance, it's better to extend the keel and/or put a bulb on the keel tip.

Of course, adding weight is almost never fast. Bilge-keels are great for shallow water sailing. Trade-offs -- you just can't avoid them.

[blueyama]

Originally Posted by CaptForce

Performance. Ok, it's true, - I don't have a "performance" boat, but that is the best answer.

I notice that you own a Morgan. Is this the boat that has bilge keels!?

Originally Posted by SimonV

True bilge keels have been in use for hundreds of years, usually a small stumpy strake the length of the hull just below the water line.

I'm a bit confused about the use of "strake". Isn't a strake a building term for a long plank running down an edge of a boat? I'm still catching up on my nautical terms.

Originally Posted by Paul Elliott

The downside is lots of additional wetted surface. If you want to reduce heeling and improve performance, it's better to extend the keel and/or put a bulb on the keel tip. Of course, adding weight is almost never fast. Bilge-keels are great for shallow water sailing. Trade-offs -- you just can't avoid them.

Very good reply "Trade Offs" are all too true it seems and I didn't really think about the added wetted surface. Would the performance added by the reduced heeling make up for the extra wetted surface in a good blow? Or could one just carry more sail area to make up for the loss in performance?

[Hudson Force]

'No bilge keels on my Morgan and none that I know of on US built boats. The most common bilge (twin) keel boat I see is the Westerly from the UK. I think Moody made some twin keel boats too.

[djmarchand]

Blueyama:

If what you are after is stability, then bilge boards will do almost nothing and may actually cause more heel. That is because the board is typically not ballasted so it adds nothing to stabitlity. It will reduce leeway, but in so doing will add more overturning moment which will cause the boat to heel slightly more.

Bilge boards or keels (ballasted) have to be integrated with the hull structure: bilge pan or the floors and stringers and would be almost impossible to add to an existing monohull.

[blueyama]

Originally Posted by djmarchand

If what you are after is stability, then bilge boards will do almost nothing and may actually cause more heel. That is because the board is typically not ballasted so it adds nothing to stabitlity. It will reduce leeway, but in so doing will add more overturning moment which will cause the boat to heel slightly more.

Bilge boards or keels (ballasted) have to be integrated with the hull structure: bilge pan or the floors and stringers and would be almost impossible to add to an existing monohull.

I will admit I'm quite fuzzy on how bilgeboards work. I was under the impress they acted like a centerboard (however just off center) and thus would reduce heeling and leeward motion. If you could explain how they function that would be great!

And, like you said it would be almost impossible to add the bilge pan ( the home where bilgeboards must live ) on a GPR or cement boat however on wood or steel it could be done without too much trouble, I would imagine. No doubt with the lose of interior space which isn't usually a desirable quality.

[psk125]

Leeboards are used in many traditional Dutch boats for a number of reasons. They're relatively inexpensive, since you don't have to build a centerboard case. Dutch polders are generally quite shallow, and the boats are built with wide, flat bottoms so that they can sit upright on the harbor bed at low tide when harbors dry out. Centerboard trunks would then clog with mud, and the slot cut in the bottom of the keel for a centerboard would weaken the hull as well, which gets wracked a good bit when the water leaves it sitting on the bottom. Leeboards do not seem to be as effective as centerboards in reducing leeway, but we are not dealing with hot racing machines here. Traditional Dutch boats get their stability from the wide, flat form of the hull, not from their leeboards. Think how difficult it is to turn a sheet of plywood over, compared to a wooden pole that weighs the same amount. The form of the hull makes a big difference in a boat's stability.
Bilge boards also resist leeway, but are used mostly in wide, flat-bottomed boats like the scows that are raced on many midwest lakes. (A scows, M Scows, etc.) These boats, again, get most of their stability from the wide, flat form of the hull, not the bilgeboards, which are not overly heavy.
As other posters have already mentioned, the best way to increase stability in a monohull is to lower the weight in the keel, or to add to it. This increases the lever arm of the forces working to counter the sails, which are what make the boat heel. People sometimes do add a lead shoe to the bottom of their keel. It adds the maximum stability without unduly increasing wetted surface. Adding strakes may help to dampen rolling - somewhat like the stabilizer fins that cruise ships use to keep passengers from getting bounced around - but they are moving at 20 knots, and have thousands of horsepower to apply against the added drag of the fins. You don't. Strakes might slow the roll, but would probably not decrease it. Some powerboats have vanes that they can rig up to steady them against rolling, but again, they have power to burn that you don't. Putting in bilge boards or leeboards or additional strakes will not achieve your goal. If your boat is too "tippy", the best solution is to add weight to the bottom of the keel, or to reef your sails.

[Bash]

Bilgeboards? I always thought those were training wheels.

My bad.

[blueyama]

Originally Posted by psk125

... If your boat is too "tippy", the best solution is to add weight to the bottom of the keel, or to reef your sails.

Thank you PSK your information was very helpful. I'm still a little fuzzy on minor details but the main idea has sunk in. The flat bottom idea makes good sense and its not the leeboards/bilgeboards that truly make the difference with stability but rather the flat bottom with these boats. I had heard of the scows being a racing boat and this is what lead me to think about added performance and so on. I wasnt sure if this would work on a keel boat but now I see it wouldnt make much sense to do so, unless there are other benefits that we have not discussed. From your comment and others it seems that added keel weight or length would be the better way to go, unless I had a extremely shoal boat.

Originally Posted by Bash

Bilgeboards? I always thought those were training wheels. My bad.

BTW
Mr. Bash, what you've just said is one of the most insanely idiotic things I have ever heard. At no point in your rambling, incoherent response were you even close to anything that could be considered a rational thought. Everyone in this forum is now dumber for having listened to it. I award you no points, and may God have mercy on your soul.... ~ Billy Madison ( slightly modified version )

[SimonV]

[QUOTE=
BTW
Mr. Bash, what you've just said is one of the most insanely idiotic things I have ever heard. At no point in your rambling, incoherent response were you even close to anything that could be considered a rational thought. Everyone in this forum is now dumber for having listened to it. I award you no points, and may God have mercy on your soul.... ~ Billy Madison ( slightly modified version )[/QUOTE]

You need to kerb your enthusiasm just a tad, if we cant have a dig or a joke a very boring place this could be. Bash I sent you some love.

[Blue Stocking]

Originally Posted by Bash

Bilgeboards? I always thought those were training wheels.

My bad.

How so? Seriously, curious I am.

[David_Old_Jersey]

Neither Leeboards or Bilgeboards would be strong enough to support the weight of a boat when dried out.

Bilge or Triple keels on the other hand are - because they are designed that way.




Not to say that painting the bottom is easier than on a fin (unless you are 2 foot tall ) but doable at the price of getting muddy / wet - with the upside that no haulout costs .

FWIW I did once toy with the idea of adding dutch style Leeboards to a 27' boat that was built on an (unused) ships liferaft as she drew only 2'6" and sailed a bit sideways, and with a modest rig meant she also liked a F4 - and going downhill . But would plough through anything, under power. Rolled like a pig though . My answer was doable - but couldn't be bothered .