Weighted Keel

[delevi]

I have been quite intrigued by a posting Duane Dunn of a new concept M boat, developed by Blue Water Yachts and Roger Macgregor. This boat includes a 450 lb lead bulb at the bottom of the dagger board. I emailed Todd at BWY to see if the bulb may be an option they will offer in the future. He replied to me that it wouldn't be, since the entire boat design was tweaked to make this all happen. However, he said that they are working on an option to shoot 50 lbs of lead into the current 26M dagger board and this, they believe will have a reasonably good improvement to the boat's stability and reducing heel. Sounds like a nice upgrade for those of us who sail in heavy winds. Im wondering if this will require a small winch to deal with the extra weight, and how much improvement in stability one can reasonably expect. Any thoughts?

[Chip Hindes]

My thought would be that it's a waste of time and effort.

I believe the optimum angle of heel is stated to be 15 or 20 degrees max for the X, what about the M? I don't have all the numbers, but with some guesses, at the shallow angles of heel where the Mac operates best, the additional righting moment will be about 70-90 lb-ft; less than that provided by (say) moving a small child from the boat centerline to one of the cockpit seats.

The effect would be more beneficial at more aggressive angles of heel, but it seems to me that's a place where you don't want to be to begin with.

[Frank C]

.... I emailed Todd at BWY to see if the bulb may be an option they will offer in the future. He replied to me that it wouldn't be, since the entire boat design was tweaked to make this all happen. However, he said that they are working on an option to shoot 50 lbs of lead into the current 26M dagger board ...

Leon,
Chip's right, a +50-pound DB is a waste of money. But an owner who wants to carry full sails in higher winds (you qualify) will surely duplicate Todd's bulbed DB someday.

Regardless of the other fancy upgrades, even a 150# bulb hanging 5 feet below the hull is going to add significant stiffness. At that weight, it might even be recoverable from a hard grounding, and could be lifted with a simple deck tackle. You'd need to experiment w/ building the correct board to carry a bulb, and you'd need to change the trailer to longitudinal bunks. Payoff would be a faster boat in higher winds, and prolly a great sideline business oppty!
Just think of all those sacrificial boards that will need replaced!

[delevi]

Chip & Frank,
Thanks. You probably saved me a few bucks and some disappointment. I guess I'm desperate for mods to improve boat stability.... in high winds the Mac sure needs it. I like the idea of the 150 lb bulb Frank, but I'm not the engineer type. I guess I'll have to wait for someone else to come up with the contraption. Moe, this might be right up your ally...???

[Richard O'Brien]

i think something might be possible for the M. I have more trouble with a swing keel. I can imagine someday casting a couple of feet of bronze keel designed to slide inside a 1/4" to 3/8" thick epoxy sheath. It would slide down to a 7' or more creating a lot more leverage. It would lower after the regular daggerboard caught, and simply slide on down. Same shape only smaller. If it were correctly weakened in back, it might be a breakaway, or sacrificial weight in case of grounding. I have all the stuff for the molds, and castings. but the engineering might be a little tricky? Oh well! always got to have a few daydreams. [/b]

[Moe]

Keep in mind that the centerboard/daggerboard contributes to heel as a result of fighting leeway. Anything you do to make the board more effective, including increasing it's length and depth in the water, will increase its contribution to heel. That may give the weight more leverage to fight heel, but it also gives the leeway more surface area to act on, and that additional surface area down low has more leverage to heel the boat. Obviously, it will also increase drag.

BTW, this isn't right up Moe's alley... it's right up Chip's. But I agree with him. The most effective use of additional weight to fight heel is going to be applied as rail meat.

[Richard Lisch]

Hi everyone,

don't you guys think that the main problem is not the weight or length of the board but the moment applied to the dagger board box, once the boat is heeling.
I believe the way the box is made it would break in an instant and sink the boat.

[Duane Dunn, Allegro]

From what Todd told me they made structural changes in the daggerboard trunk area. They removed all the fixed ballast which is a resin and sand mix and then beefed up the trunk. At this time the bulb is completely external to the hull, but he felt if it ever went into production a cavity would be made so it can at least partly recess into the hull. He didn't mention any problem with the trailer. I beleive they just use a multipart tackle to raise and lower it.

From the way my X loads, on most ramps there is at least 12" of clearance at the rear and center bunks as the boat floats in. I don't think there would be any problem using the trailer as it is. The trailer is at an angle on the ramp while the boat is level on the surface above it. It's not until you pull out that the boat settles into the rear bunks. Mind you, I sink my trailer just until the fenders disappear below the surface. This allows the boat to float in free all the way up to the small forward vee bunk. Todd also indicated that the drag of the external bulb cut 2-3 Mph off motoring speed, although this isn't that big of a deal with the 70 Suzuki that is BWY standard motor.

[baldbaby2000]

I wonder if adding weight to the bottom of the dagger board really stresses the trunk area much more. I would think the sideways force on the boat due to the wind is what's significant. Adding more weight to the board seems to be no worse than adding "rail meat" if the boat is kept at the same angle in both cases.

The 50 lbs of lead option doesn't sound like much, but if the boat goes to 30+ degrees in a gust, it may be quite noticable. As the boat heels the crew weight moves more towards the centerline and becomes less effective whereas the weight on a keel becomes more effective.

I've already added a pulley to get more purchase on the standard board. One could easily add addition pulleys for more purchase in raising a heavier board.

BB

[Graham Carr]

Rail meat may be fine if you have others onboard, but when you sail alone your out of luck. This is when I feel a modified weighted keel would be beneficial. Im not so sure 50 lbs would be sufficient. Adding more weight as Erik Hardtle did would be needed. You can see his mod here. I plan on doing a mod similar to this on my 26-X. I will use my original keel as a pattern and then save it for later use as an emergency back-up when on long journeys. I will be building a new keel that will have a thick stainless steel plate with dense foam glued to the plate. The foam will then be shaped as need. Lead will be shaped and attached to the end on the board. This will then be encapsulated in glass. The pivot pin will be beefed up as noted in Eriks post. I hope to build this during the upcoming winter.

Similar to what Duane describes on the proposed M factory mod, Bill Teplow did such a modification to his potter 19 with great success. Here is an overview on a story from the Small Craft Advisor magazine. His detailed construction / testing article can be found in the, Issue #27 May/June 2004. You can order the back issues from the SCA website; www.smallcraftadvisor.com or call them at the number posted on their site. I have no financial affiliation with them. I am just a happy subscriber to their great magazine.

Bill sails a West Wight Potter 19 named Chubbys. His home port is Berkeley California. This intrepid sailor has sailed his potter from Berkeley to Hawaii. Port Angeles, Washington up the inside passage to Glacier Bay Alaska then back around the outside to Craig Alaska and then South from Seattle to Berkeley California. After his Hawaii trip he decided to modify his stock keel by adding a led bulb to the keel. His goal was to improve sailing closer to wind, increasing the righting moment and stiffen the boat. He attached a lead bulb that resembles a squashed football to the bottom of his new thick stainless steel, glass encapsulated keel. The potter does not carry any other ballast other then her keel. The original keel is 270 lbs. Bill added 150 lbs which puts the new keel at ≈ 417 lbs, putting the majority of it well below the hull bottom. The righting moment for the stock keel at a 90-degree knockdown is ≈ 550 ft-lbs. The new keel for the same heel angle is ≈ 1649 ft-lbs. That is a 3-fold increase in the righting moment. He goes on to state that during his Hawaii trip he slept next to the trunk and the he could feel considerable flex in that stock truck. So he did beef up the area around the base of the trunk. He did his first sea trails off the Marin coast (North of the Golden Gate). The wind was at 25 Knots with 6-8 foot seas. His shakedown cruise of 2600 miles was the trip north to Alaska and then South down the west coast to Berkeley as stated above. Bill reports that she now sails much stiffer, points higher and does not round up when overpowered as well as the increased righting angle.

Graham

PS; There is loads of space to add more then enough foam to counter the added weight in the event of holing. In fact I have added a lot already. I save any chucks I can get and stuff it !

[demian]

I sail a 26X. I find the "sudden heeling" and rounding to weather somewhat disconcerting. I would dearly love to weight the ceterboard with the hope that it would improve sudden gust and strong wind performance. Has anybody done this, what does the Mod look like, and, most importantly, how has it affected performance.

[Frank C]

Hmmm - first post - Welcome demian!

Click the blue text to check out Eric's weighted centerboard project in the Mod Pages.

It helps if you show more details on your boat, e.g. year & engine. Some add details in the profile "signature" field, or in the "location" field as shown at left.

[demian]

Thank you for the ref to Eric's Mod. The mod sounds pretty extensive, and I'm not convinced that it's necessary to re-route the centerboard wire back from it's original position. If the weight of the ceterboard is "too great" to lift manually, then purchase can be gained by block and tackle on the cabin top, plus, the winch could be used. However, I am glad to read that weighting the centerboard resulted in the heel being "slower" and that the boat behaved more like a keel boat. I kinda like that. Such a mod would be small price to pay for improved performance.

As noted by Frank C. I'm a newbie to this site so I apologise for not being "with the program". As requested, here are some details on my boat, the Artful Dodger. It is a Mac 26X - 2002 version (last of the breed) with a Yamaha F50 motor. I use a genoa on a roller furler. I purchased the boat new in 2003 when the new 26M had just come out, primarily because I preferred the layout of the cabin.

A little about me. I started sailing in dingies and open cockpit centerboards some 40 or more years ago. I've been sailing keelboats for the last 30 or so years and kinda got used to them. I purchased the Mac because I wanted the ability to sail on weekends and maybe up to about a week at a time, and I wanted to be able to trailer the boat to various areas around the Great Lakes. It's beautiful country for gunkholing.

Initially I was a little disappointed in the Mac because I wanted it to behave like a keelboat, and it doesn't. In the last week or so I finally broke down and read the "MacGregor instructions" that came with the boat. This explained how to deal with the weather helm, and rounding up issue (adjust the position of the centerboard depending on the point of sail). and it actually does work. The sudden heeling issue is still bothersome especially in 5 - 6 foot seas, so the weighted centerboard is my next project. Hopefully I'll be able to get it done over the winter.

[Tom Spohn]

Don't forget that Todd has removed about 400 lbs. from the top of the boat when he added the 400 lb keel. He did this by changing the layup schedule on the hatches, omitting the head door, and most importantly--going with composite rigging and lighter weight sails. A small weighted keel will have a greater effect if weight is removed from topsides.

[James V]

A couple of thoughts -
The dagger board has holes in it. Has anybody had the dagger board filled with sand and clog the holes?
Has anybody tried a longer dagger board?