She won't do as she's told!

[slippett]

Last year I purchased a lovely little 18ft Mevagissey Tosher, she's an open boat with a dipping lug on the main and a standing lug on the mizzen. I've sailed lots of gaffers in the past but luggers are a new beast to me, and this beast is currently getting the better of me.

If the wind is on or aft of the beam she sails like a dream but as soon as the wind goes forward of the beam the speed drops and she becomes sluggish and unresponsive. So much so that I can't really get her sailing upwind at all and tacking is definitely out, she stalls way before even being head to wind! I have tried sailing without the mizzen to see if that was affecting things but it made no difference. I have tried adjusting the point the yard hooks onto the traveller to see if that helps but no. I have moved the tack of the sail from the bow to the mast (making it more like a standing lug) thinking that the centre of effort would be moved aft but that didnt help. I've tried moving the mainsheet pulley into the centre of the boat so the sail was flatter but that made no improvement.

She had no running rigging when I bought her and her sails were old and saggy so I had her a new set of sails made from cloth/canvas. Her mast step was broken so I remade it and am now wandering if I should have raked the mast a bit, it's currently straight.

I'm getting really frustrated, she's such a lovely boat. I know dipping lugs are hard to sail in that you have all the faffing about when tacking them (if I ever get the chance) but they should be a very powerful rig.

Please help. Any suggestions why this lovely lady won't sail to windward would be gratefully received.

 

[old_salt]

Is it a boom free sail? make a quick fit boom it will flatten the sail, we did it on a Drascome 19 and it improved the performance to wind a huge amount.

 

[slippett]

It is currently boomless. I have centered the mainsheet block so the sail does flatten nicely. Would a jib improve things or would it just move the CofE too far forward? I have got the mizzen which could counteract that. There just seems no power there

 

[AntarcticPilot]

Is the ballast in the right place? If she is stern-heavy, that might result in the behaviour you're describing.

 

[slippett]

Good point! I am single handed so I'm at the tiller when tacking so my weight is at the back and the inboard is near the stern too, maybe she needs some ballast up front. I'll take a few bags of sand out with me next weekend

Thanks, a new idea! I feel excited again

 

[cliffordpope]

You could try doing a scale drawing of the underwater hull profile and the sails, and work out the Centre of Lateral Resistance in relation to the Centre of Effort.
CLR you can get by cutting a bit of cardboard to the stem-stern underwater profile and balancing it on a sharp edge. You can test that position at the quayside - it should be the point at which if you push the boat away, she moves sideways rather than one end moving more than the other - imagine being towed sideways.
CE you plot the sails, then find the centre of gravity of each triangle by bisecting each angle to plot the centre. You combine triangles by joining with a straight line, and then loading the distance along the line of their combined effect in proportion to the areas.

Finally you end up with two vertical lines on your plan, representing the distances from the stem of CLR and CE.
My understanding is that CE should be slightly forward of CLR, so that with the wind abeam or close hauled she initially tends to pay off slightly, but then turns up the instant she begins to heel. Up to the point of heeling everything is in two dimensions, but the moment the CE moves off the centre line there is a leverage effect which counteracts the initial offset of the CE ahead of the CLR. It is this interrelation which makes for directional stability - a well-balanced boat does not need massive rudder assistance to stay on course, and once balanced should largely hold a course untouched.

You can play around with this effect using a model yacht, pushing with your hand to simulate wind pressure.
Trim, eg by adjusting ballast, is absolutely crucial in altering CLR.

 

[reginaldon]

She won't do as she's told!


Marry her - I did. We've just celebrated our Diamond Wedding!