I am thinking about doing an overnight trip to a nearby island and I want to try a bit of proper navigation instead of just relying on my GPS.
Having never done this other than while taking my Day Skipper course I am not sure what to use as an average speed. I was thinking something in the order of about 3.5 knots. Any recommendations?
John
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HEMP
Average Speed
Average Speed
Last edited by jjspicer on Fri Feb 25, 2011 9:05 am, edited 1 time in total.
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Phil De Troy
- Making way
- Posts: 33
- Joined: Wed Nov 22, 2006 7:00 pm
- Location: Seneffe (Belgium)
Average Speed
John,
I think it is realistic.
The Swift has almost the same performances as the First 18 (PY 1111 and 1102), and handicap tables of the French Sailing Federation ae giving an average speed in racing 3.88 knots.
So for a boat, not necesarily in racing condition, reduce by 10%, and the result is 3.49.
But I had another calculation method for long distance cruising on a larger boat (26 ft, quarter toner converted to cruiser), for cruise planning, it was 75 NM per day. The principle was never to go further than 75 miles per remaining day for the cruise. 75 NM/day means 3.1 knots, this is slow, but this is the effective VMG upwind when the boat was tacking at her best in force 3 or 4.
Usually, when things were going well, I could stop for one night after 36 hours half wind or even (once in 20 years) spend 1 and a half day after 24 hours downwinf with spinaker in a strong breeze. But sometimes I had to sail 5 days and 4 nights to gain one night in harbour.
This boat had a reference speed 4.54, so if you reduce 75 miles to the size of a Swith, it means 64 NM/day, or no more than 2.7 knots
Phil
I think it is realistic.
The Swift has almost the same performances as the First 18 (PY 1111 and 1102), and handicap tables of the French Sailing Federation ae giving an average speed in racing 3.88 knots.
So for a boat, not necesarily in racing condition, reduce by 10%, and the result is 3.49.
But I had another calculation method for long distance cruising on a larger boat (26 ft, quarter toner converted to cruiser), for cruise planning, it was 75 NM per day. The principle was never to go further than 75 miles per remaining day for the cruise. 75 NM/day means 3.1 knots, this is slow, but this is the effective VMG upwind when the boat was tacking at her best in force 3 or 4.
Usually, when things were going well, I could stop for one night after 36 hours half wind or even (once in 20 years) spend 1 and a half day after 24 hours downwinf with spinaker in a strong breeze. But sometimes I had to sail 5 days and 4 nights to gain one night in harbour.
This boat had a reference speed 4.54, so if you reduce 75 miles to the size of a Swith, it means 64 NM/day, or no more than 2.7 knots
Phil
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From: jjspicer (forum-lounge@swift18.org)
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Sent: Monday, October 20, 2008 3:43 AM
Subject: [Swift 18] Average Speed
I am thinking about doing an overnight trip to a nearby island and I want to try a bit of proper navigation instead of just relying on my GPS.
Having never done this other than while taking my Day Skipper course I am not sure what to use as an average speed. I was thinking something in the order of about 3.5 knots. Any recommendations?
John
Phil De Troy www.MicroClass.org