Anonymous asked in Cars & TransportationBoats & Boating · 10 years ago

how much speed (maybe percentage-wise) would you lose sailing a 420 with a main sail and not using the jib?

3 Answers

  • 10 years ago
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    there is no right answer to your question because of all of the variables involved. the main sail is not as efficent as the jib because th mast interrupts the flow of air on the leading edge. going to windward air flow from the jib increases the air flow around the main (slot effect) which creates more power and faster boat speed.

    in light to moderate winds, having the both main and jib up is considerately faster than main alone. in higher winds when the boat is overpowered, the difference in speed under main only vs main and jib will not be as great (as in ligher winds).

    proper sail trim is also a big factor. the wind is rarely constant, instead it will vary in strength and direction, having both main and jib up will allow you to adjust boat angle and sail trim to power up or down to maintain max speed. this is harder to do under main only.

    that said, if you are sailing with out crew the 420 will still sail on all points of sail under main only.

    hope this helps

    Source(s): over 40 years small boat sailing, racing cruising etc.
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  • 10 years ago

    While I don't know the 420, I have sailed GP14s for many years, and I would expect that in this respect they are comparable.

    The GP14 WILL sail, if required, on any point of sailing - including to windward, under either main alone of genoa alone. However progress will be painfully slow.

    Main alone can sometimes be a very useful gambit for the first few yards when clawing off a lee shore, where you need to wade the boat to sufficient depth to get at least some centreboard and rudder down, and then get her pulling to windward absolutely immediately you get aboard. In those circumstances, having any sort of headsail set can put you back ashore before you can get way on the boat. But that situation is the exception, in that it lasts for only a very few yards until you are in deeper water.

    That apart, I have found many times over a period of perhaps fifty years that although the boat can be made to sail under either sail alone, she will be slow, and not particularly close winded. The boats that I have owned in more recent years have been very fully equipped with seriously good reefing systems, and with that option available I am absolutely convinced that she handles better, and in particular will go to windward better, under a combination of both sails suitably reefed rather than either one sail on its own.

    One prime example occurred two or three years ago on Anglesey. My crew, a comparative novice, and I had arrived with a view to possibly sailing on a day which was at best marginal. We rigged the boat in the shelter of the sailing club, and pulled down the first reef in the main; by the time we reached the water's edge the main was slamming around so violently that we pulled down the second reef and I decided to try the conditions under main only, so we left the genoa fully furled. We set out, and after a few minutes decided that it would be foolhardy to continue, so headed back. The return involved a beat, and to help her point we then unrolled just a pocket handkerchief of genoa.

    However the counter to that is an incident last August, off the same coast, when the cruising fleet were caught out in an unforecast force 7/8 off Point Lynas - this on a forecast of force 3, with perhaps 4 later! The one single-hander in the fleet capsized and inverted, and I stood by him.

    On that occasion, with the unusual requirement for best possible stability in gale conditions and minimum speed, I first pulled down the two mainsail reefs in quick succession, and then dropped the main altogether, and stood by the casualty under heavily reefed genoa and nothing else. Once the lifeboat had rendezvoused with the casualty, and we had been relieved, we then shook out part of the reef in the genoa and resumed our passage, but since we were no more than beam reaching I was quite content with reefed genoa and no main, and we were still able to make securely against the strengthening ebb tide.

    Hope this helps.

    Source(s): A lifetime of sailing small boats, yachts and dinghies, and about 25 years of teaching sailing and seamanship.
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  • 10 years ago

    Probably 20% - or so near it, that it wouldn't make much difference. I don't understand why you would want to do such a thing? A fully equipped sailboat utilizing the jib is absolutely the most maneuverable and easy to sail and easy to handle configurations there is.

    Happy & Safe Sailing,


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