weighted dagger board.

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trebor
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weighted dagger board.

Post by trebor » Sun Jan 04, 2015 9:39 pm

would a weighted dagger board help to right a dinghy?
I am thinking something like a GP14/Enterprise type of boat, the helm would not be concerned with loss of speed.
would it also have an effect on capsize liability?
what effect would it have if boat was inverted?
would a dagger board work better?
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Re: weighted dagger board.

Post by ent228 » Sun Jan 04, 2015 10:06 pm

Uffa Fox thought that when Int 14 was not as good for sea conditons after the heavy bronze center plates went out. I think he had ones in the 60lbs range.

So a weighted dagger board would certainly help.

Access dinghys have a hollow weighted dagger board it's about 50mm thick. (30kg?) that extends about a meter from the bottom of the boat. They do capsize but won't invert (well I have not managed it yet). When the sailor is in the water free of the boat they flop up.

So yes make a dagger board with a weight in the end and add a foot or so extra length to give a really beefy righting moment.

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Re: weighted dagger board.

Post by Ed » Mon Jan 05, 2015 3:18 pm

I have very mixed feelings about heavy centreplates.....

I have sailed Jollyboats and Fireflies with a mixture of heavy and light plates.

The first Jollyboat I sailed had a bronze plate (not too surprised that was stolen), then also sailed with the 65lb steel plate, an aluminium plate and a wooden board.

My preferences lie strongly with having the lightest (and thickest) board you can carry. Stiffness, shape and a good fit are also worth striving for. A lighter boat simply performs better, is more agile and is easier to move and manhandle on the water, and often more importantly on land. If you are happy with handling your boat, and can sail it properly, then a heavy board offers very little. If you are keeping the boat upright, then there is no moment for the weight to work with anyway, and the weight is simply slowing you down and damping the movement. The chances of turning turtle are lower, but if you did, say due to the tide pulling the rig under the boat, then you could possibly have a real problem with a heavy plate. I will let you go the math, but a 65lb weight falling approx a metre back into the case, would I think be quite likely to break straight through the centre-board case. It should also be noted that manhandling a heavy plate into and out of a dinghy can be a little dangerous and certainly when done over the water on quay or pontoon, used to make me feel quite nervous. Also there is a much bigger worry about catching fingers etc etc in a heavy plate.

So on the face of it, not much going for it.......but....
A heavy plate does make a boat easier to sail for the beginner. It makes it much more tolerant of mistakes, it makes it intrinsically more stable, as all rocking is damped by the weight. Of course the important thing is that it becomes more and more effective, the more rocked over you are, so when you really notice it is when you are in a possible capsize situation. When this happens in a lighter boat, you would of rocked too far, the wind would be under the hull, your weight may not be commited where it should be etc etc, and over you would go. But in this situation with a heavy plate, as you start to go over, you loose power in the sails, but gain a moment to return you to the flat from the plate. You have a much higher chance of recovering from a blown-flat situation, albeit often full of water.
Then, say you do go over......the boat fills with water, the sails loose their power and often the boat will come up again simply due to the weight of the plate. This is certainly so if you also have a wooden mast, but even with a tin mast, bringing it up will be much easier......but then of course you may well have 65lbs more water in it to remove before getting sailing again. And the waterlogged boat will be much heavier too.

So depends on what you want out of your boat and your ability level.

Certainly wouldn't discount it for a learner boat, but in the end, you will be better off with a lighter board.

cheers

eib
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Re: weighted dagger board.

Post by trebor » Mon Jan 05, 2015 3:40 pm

Ed, I was thinking more along the lines of a cheap sailability/keel boat, their are several old boats at club this could work on, the idea came about due to having several older members who can still sail but would only be able to go out in the lightest wind conditions, this would hopefully extend wind range.
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Re: weighted dagger board.

Post by ent228 » Mon Jan 05, 2015 6:29 pm

Hopefully the dagger/centerplate would be locked down with a pin.

If you had an old Mirror you could easily replace the dagger board case with a wider one and use an Access type keel, you could even go as far as a central Access style seat.

Borrow an Access keel from your local Sailability group and experiment over the winter.

On another tack, steering in Access dinghies is about the worst I've ever had the misfortune to experience, so if you went down that route a solid rod from the rudder head to make a push pull system like very old ICs used to have would be much bettter.

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Re: weighted dagger board.

Post by trebor » Mon Jan 05, 2015 8:45 pm

The boat would be sailed by people who can actually sail, they would just find it "difficult" to "impossible" to recover from a capsize, this would not be an official club sponsored job, it would just be there.
The more you look at it, the less likely you are to actually do it, unless it was for yourself.
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Re: weighted dagger board.

Post by jpa_wfsc » Sat Jan 10, 2015 9:46 am

In the kind of weather in which one actually capsizes, to right a capsized boat of sailing equivalence to a GP14 you need about a grown adult's weight acting towards the end of the fully extended centreboard... due to the combined counterbalance weight of mast, sails and water in the sail.

Much less for a Mirror - a typical 9 yr old child can right them once they have got onto the board.

When you think about it - it is quite a lot of weight. I was astonished when my Skua capsized that its 60Lb steel centre plate with 80lb lead bulb at the tip would not self right - it needed some help from me. That was an 18 foot boat with Wayfarer sized rig.

It is therefore much better to sail something designed that, or sail in a way that, capsize is not likely... hence the development of access dinghies etc. I'm not convinced that modifying a standard dinghy with a weighted board will help a lot, and will (as others have said) certainly affect the sailing experience.

At Whitefriars we have (and have had) a good range of accessible boats and I have had the opportunity to sail most of them. Best sailing experience is from the Martin 16 (a small keel boat, not a keel assisted dinghy) and from the Challenger Trimaran. Almost as good is the two sail Liberty (there is a range of access dinghies, from the slow and terribly sailing 303 upwards!). The Martin, Liberty and Challenger deliver very different experiences but each is a 'pure' design, meant to do the job it does, rather than an adapted and thus compromised dinghy would be.

I am sure that demo sails can be arranged for you if you want - pm me and I will get you in touch with the relevant people..
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Re: weighted dagger board.

Post by trebor » Sat Jan 10, 2015 11:35 am

Hi Jpa,
Thanks for offer, I have seen boats you mention at Whitefriars, our committee are reluctant to take this step, it is the age old problem of a few doing the bulk of the work and reluctant to take on more, also they have had volunteers offer to take on a new job and then dropping it after a couple of months (like a child promising to look after a puppy) and they have been saddled with yet more work.
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Re: weighted dagger board.

Post by chris » Sat Jan 10, 2015 12:31 pm

I have a merlin and an Int14 with lead tipped boards ( and heavy but buoyant wooden masts). and one slightly later merlin with a plain wooden board and tin mast. The weighted boards are about 20lbs I think.
The unleaded merlin used to turn turtle quickly but a little extra buoyancy under the side decks cured that by moving the effective pivoting point nearer the mast, but it floats a little higher than I would like for getting back on the board. Righting the boat is OK, getting back on board - not that easy now! ( I'm the wrong side of 60 but reasonably able ( I was going to say 'fit' but that may be untrue!). The other boats with the leaded boards are no easier to right really but then you are lifting a heavy mast. They float lower in the water, though , so the board is easier to climb on. They won't turtle and the old merlin has large rolled side decks so that (in theory) the boat is buoyant on it side even if there were no bags in it.

I see your problem as twofold 1, reducing the chance of a capsize, 2, making recovery easier.

1, Instead of weighting the centreboard how about trying a lightweight carbon mast and/or a cut down sail. Second hand carbon masts are becoming more available, but you could probably borrow one to experiment with. See if it makes the difference you want. It may be technically out of class but that doesn't seem to be a serious factor for you. (Local handicaps can be adjusted anyway).
The other thing is getting the buoyancy right ( once you have capsized) too much and low down will lift a lot of the boat out of the water getting the board high and tending to turtle. It also means the helm will be working against the whole weight of the hull to right it. If it is all close up under the deck at the widest part it will be much easier to right, as the weight of the hull is helping you; it wont float so high make the board easier to get on but it will come up very full of water ( easier to get back on board but not really the situation you really want either!) So a combination works best in my opinion. Righting lines, knotted ropes, rope ladders may also help the less bendy helms get back in.

If you want to try a heavy board though, I have and old steel one you are welcome to have and do whatever you want with it.
Chris

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Re: weighted dagger board.

Post by trebor » Sat Jan 10, 2015 2:30 pm

Hi Chris, I have decided not to do this conversion, thanks for kind offer.
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Re: weighted dagger board.

Post by Michael Brigg » Sun Jan 11, 2015 11:48 am

I would be against weighting plate or dagger board for almost every thinkable reason.

Going back to Uffa Fox one of his better and more perceptive quotes was to say that "Weight is only useful in a Steam roller."

What are you actually trying to achieve? A sailability Boat, or boat that is good for a beginner? If the latter, then the needs of a disabled sailor are just the same as the able bodied. It must be easy to handle and not oversensitive to mistakes. If it is the former, then it is the specific needs of the sailor that must be catered for. but should be otherwise every bit a twitchy as any other competitive boat. Sailability sailors do not have lack of skill or wit any more than the rest of us, and those that enter competition are keen to compete on a level playing field where there is no hint of patronisation. Most importantly they want to make their own choices.

You only need to watch a game of "Murderball" to see that disabled athletes do not want any quarter given. and often have skills to adapt to their chosen sport, that are well beyond our own able bodied abilities.

Image

...so, if you are looking for a boat that can be raced by a sailability person, then it must be competitive at every level, and weighting the daggerboard will do nothing to achieve this. It just makes the daggerboard more difficult to use, (presumably it would need locking system or a cumbersome up and don adjustment. That is the last thing a disabled sailor would want, adding handicap onto handicap.

If you want a "uncapsizable boat, then you need to de-power the rig. With our children we put them to sea first of all in boats like Optimists. With less sail area. In every situation this makes the boat easier to handle. As your sailor becomes more skilled the choice to go out in heavier conditions is catered for as the boat remains easier to handle.

Consider the cause of most capsizes. Upwind it is (mostly,) some would say exclusively due to handling errors though too much canvas is often part of the equation. Downwind, the boat becomes easier to handle as it goes faster with the weight of wind in the sails being reduced by subtracting the speed of the boat. On an immediate level this is first done by reducing the rig, and with increasing practice and skill, by going faster. A weighted dagger board will not help in either scenario. A heavier boat will not plane, and so with greater weight of wind in its rig, is more difficult to sail.

It is far more important to look at the ergonomics of the boat. Where are the control lines, how easy is it for the sailor to move about? Any disabled person spends their life adapting to being different, and they are usually very good, (better actually) than able bodied ate using "what is available" in order to use "normal" equipment. (That is not to say that a few adaptations such as seating and handholds will help ...but most important, how good is the sailor? Do they have all the necessary decision making skills? In the rush to get a disabled sailor afloat. this is easily overlooked and must be managed just like any other sailor mainly by appropriate instruction and a good well organised "Safety boat" team, (which engine dunking aside :D :oops:) you seem to be very well catered for.

Having said all of this, I do not wish to seem obstructive to the principle of sailability, and sailing as a sport is uniquely placed to give disabled (and adaptive) sailors the freedom enjoyed by able bodied sailors. I truly admire your club in its efforts to provide and develop appropriate boats. It is an area where many richer well established clubs could take an example.
Michael Brigg

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Re: weighted dagger board.

Post by trebor » Sun Jan 11, 2015 12:39 pm

Hi Michael,
This boat was not intended to be used by disabled sailors, we do not have facilities to deal with disabled sailors, their is a centre a couple of miles from us, run by professional instructors, who have a full sailability set up with cranes, keel boats etc, I did RYA level 1&2 there, the sailability fleet were running a race whilst I was training, when I accidentally got in the way of the lead boat, his language was enough to convince me how seriously it was run.
The boat would have been used by older sailors, who have extensive experience, they would not have raced, the boat would be used purely for pleasure.
The club would have no official input into this boat, it was to be purely a private venture.
I have however has I stated before, following the advice received from yourself and others decided not to continue with this project.
Rob.
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Re: weighted dagger board.

Post by Rupert » Sun Jan 11, 2015 1:20 pm

I'm not 100% convinced that it is such a bad idea, especially in a boat that sails well when heeled a little (so the keel is working), and especially in a boat not designed to plane. In a boat like a solent Scow a heavy plate is part of the boat - it makes sense, and makes the boat have the characteristics that it does.

Now, in a boat being converted (Rob, I know you aren't now planning to, but it makes a fun paper exercise) you can rule out certain boats straight away, I feel. Too light a hull, designed to plane early - is that the Enterprise out? Sails well heeled - any boxy hull (the GP14? is out - they are horrible when heeled over). So, we need a round bottomed boat that sails well in displacement mode.

You know what - that boat is out there, and has been from 1947, and does have a big, weighted plate - the Swordfish. Put a smaller sail plan on, and you'd have a great boat for the older person. Now, take that to its logical conclusion, and the Albacore should be able to cope too, being the same hull shape.
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Re: weighted dagger board.

Post by Ian Malcolm » Sun Jan 11, 2015 2:08 pm

Early Albacores had metal plates. I fitted one in my 60's boat for coastal cruising and was entirely satisfied with the boat's handling and performance with one. Obviously its not good for sheltered inland waters racing though.

A good setup to control one is a Holt Alllen drum winch (for kicking straps) for the uphaul and a simple line through a plastic V or clam cleat to cleat it down. Its essential that the downhaul can give if you hit something, but it must be strong enough to hold the plate if you ever invert in a capsize. Obviously, one takes care to keep the downhaul cleated off in heavy weather and stay in deep enough water.

I described it with photos here several years ago.
viewtopic.php?p=9854#p9854

Stuff smaller sail-plan as that's totally boring in light winds. When I replaced the main I specified two reefs, with the second reef taking the head of the sail right down to the top of the forestay.
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Re: weighted dagger board.

Post by trebor » Sun Jan 11, 2015 6:26 pm

OK, if we are going to design a self righting/dificult to capsize boat (on paper) how about fitting a set of heavy foils ( I do not know proper term for foils used on Moths, but those type) on the bottom of board, would the foils lifting boat out of water counter extra weight ?
could they also be adjusted individually, ie 1 up 1 down to counter heel ?
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