Refit - New Sails & Bowsprit.

[dip_lug]

A 19 foot ketch, built in 1979, Northern Star, is a replica of the 1850s No Man’s Land Boats, use of the eastern United States. But after almost 25 years I’ve decided to replace the dip lug sails with Gaff or Gunter sails.

Lug sails have several inherent problems. The obvious, is the routine of dipping on each tack. They are inefficient to windward when compared to other sails. They do not hold a shape when reefed. In heavy weather, the yard often becomes a dangerous un-tethered missile when sail is raised or lowered.

Present configuration.
Main mast is forward enough to be a Cat boat. Mizzen is approximately three feet aft of centre line. Present sail configuration produces a heavy weather helm on a reach when under full sail. With only the mizzen set and tiller tied off, the boat will heave-to when driven into the wind. Both lug sails are free footed.

Proposed configuration.
Main and mizzen masts, gaff or a gunter with boom.
Addition of a bowsprit in order to add a foresail(s).

My thoughts on the configurations.
Sails
As per the original boats, Northern Star has relatively low masts; Main - 18 foot; Mizzen 14 foot. A gaff would have a low peak and the boom must be high enough to clear unwary heads. Both these factors would require small main and mizzen sails. By its design a gunter would have a higher peak eliminating one of two factors of the smaller gaff sail. However I know nothing about the gunter’s performance.

Bowsprit
I’ve been unable to find out any information as they apply to smaller boats, or the pros and cons of adding a foresail

I don’t want to take on this refit going at it completely blind relying on the trial and error method. It could be frustrating and expensive!

Your ideas or suggestions would be very appreciated.

Cheers, Colin.

 

[Peterduck]

Some thoughts: A standing lug rig is much easier to live with in close quarters than the dipping lug. Gunter rig is very under-appreciated and quite efficient. It also allows you to use short spar lengths. In planning your new rig, calculate the individual sail areas and the centre of each sail. Measure the distance between each sail centre and a fixed reference point, say the mid-section of the hull. Multiply these distances by the area of the sails, and give the moments ahead of the centre a positive value, and the moments aft a negative value to arrive at the Longitudinal Centre of Effort of the sail plan. Work out the area of the profile of the underwater section of the hull and its centre. Arrange the L.C. of E. of the sail plan to be about 10% of the waterline length ahead of the centre of the underwater area. This may not be the final best place, but it will be close enough to make a start. Only fine tuning of the rig on the water will give you information to change it from there.
Peter.

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[dip_lug]

Peter.

Thank you for your suggestions on the proposed refit. I spent several hours on the Net last night and I’m inclined to agree with you regarding a Standing lug sail. One of the advantages of a lug sail is the relatively low mast, that require no standing rigging providing the mast is stepped and braced securely.

I will probably start with a Standing lug, this will certainly eliminate the “un-tethered missile” problem and may even help the windward ability. If not, I will then consider adding a boom to the main and possibly the mizzen to make a balanced lug. Once this is done I’ll work on the weather helm. This allows me to work in simple steps addressing one problem at a time.

I have decided against the Gunter. As someone suggested to me in another forum “I think Northern Star looks stunning as a lugger, and might look a little odd as a gunter rigged ketch (my opinion only). The gaff rig might look more appropriate.”

Cheers Colin.

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