Voyage time calculation question (and a poll).

[Rum_Pirate]

Planning a circumnavigation of St.Kitts (St. Christopher) on Saturday :

IE

Yacht is a Corsair F-27 trimaran.
It is fairly swift, speeds around 15mph have been achieved in the six short sails we have been on so far.

Distance is +/-55 miles, rounded off to allow for the up channel leg.
Wind direction is a constant 13 knots (15 mph) from East, with some gusting to 16 knots (18.4 mph)
There will be some wind shadow (+/- 6 miles) in the lee of the 3,000 foot mountain.
Seas anticipated at +/-1.1 metres with +/-8 seconds between peaks.
NE side of island is exposed to Atlantic (wind and waves heading a Westerly direction) while the SW side is 'sheltered' and a bit calmer.
There naturally being a circumnavigation will be some sailing to leeward, a fair bit of beam sailing, and some to windward.
No motor sailing anticipated.



Surely it is not as simple as 55.0 miles / 10.35mph (Trimaran may likely average least 9 knots (10.35mph) or more)= +/- 5.31 hours.

How do you calculate the length of time to complete the proposed voyage?

See Poll and state how long do you guesstimate it will take (to nearest 1/2 hour)?

 

[newtothis]

45.8 nautical miles/9 knots (what is this mph nonsense?) = 5.1 hours = 5 hours and six minutes. Give or take.

 

[ChromeDome]

Unless youre trying for Guniness World Record just relax and enjoy the cruise.

You'll be there when you arrive - approximately.

 

[Blueboatman]

Go on then
Six hours
All in daylight and ending @Beach bar

 

[SaltIre]

I voted for over 8 hours, because I fear the voyage won't be completed.
The proposed route shows the vessel will make landfall by running aground between Sandy Point & Palmetto Bay, somewhere near Half Way Tree - or perhaps Bloody Point. I urge that the skipper reconsider the passage plan.

 

[KevinV]

I'd be going wider round poisson (?) point - shoal+Atlantic swell+waves= very uncomfortable, and reefs are often woefully badly charted

That, plus staying further out of the lee will add a few miles but benefit boat speed. I'll go with 5.5-6 hours.

 

[SaltIre]

I'd be going wider round poisson (?) point - shoal+Atlantic swell+waves= very uncomfortable, and reefs are often woefully badly charted

That, plus staying further out of the lee will add a few miles but benefit boat speed. I'll go with 5.5-6 hours.

Indeed. They've already named a Beach Bar & Grill in honour of Rummy's proposed voyage...

 

[Rum_Pirate]

Indeed. They've already named a Beach Bar & Grill in honour of Rummy's proposed voyage...

That has been my regular watering hole for years.

 

[Buck Turgidson]

6-6.5 although I'm now thinking longer. last leg will break your heart after racing to the northwest turn.

 

[Rum_Pirate]

Latest update on weather forcast




There is still time to cast your vote.

 

[Rum_Pirate]

Departure from the mooring is planned to be 7:00am tomorrow.

PS That will be noon for you lot in UK.

 

[Storm Free]

Who cares?

 

[Blueboatman]

Now here’s a thought
Which way around trends more favourably?

Drift: I always forget come April 1st, but a clockwise round the isle-of-Wight race ‘ insider rumour’ would be a contender for a good wind up I believe, if done well..

Happy sailing D

 

[sarabande]

Who cares?

Anyone who knows Rum, and his story of buying a proper boat at last, cares.

Its a major voyage for him. Be kind.

 

[Rum_Pirate]

Who cares ?

Actually I do.

It doesn’t matter if anyone else doesn’t.

The OP was made as an enquiry (see last two
sentences) and as a topic for discussion.

Everyone is welcome to join in.

BTW Welcome to the forum.
Looking forward to reading your posts.

Storm Free​

New member
Joined 29 Aug 2022
Last seen Yesterday at 16:14
Messages1

 

[Chiara’s slave]

The best F27 time round the Isle of Wight is just over 5 1/2 hours. I’ve done it in 6 hours 48 mins. That’s less distance, and potentially less tacking. Watch out for the gusts on the downwind legs. Bear off in the gusts, head up in the lulls when sailing downwind in gusty conditions. 20kn of wind is a lot on a beam reach on your boat. Good luck, sail safe.

 

[Storm Free]

Anyone who knows Rum, and his story of buying a proper boat at last, cares.

Its a major voyage for him. Be kind.

Sorry, wasn´t thinking

 

[Storm Free]

Voted for 6,5 to 7h - should allow enough time for early afternoon cocktails

 

[SaltIre]

Voted for 6,5 to 7h - should allow enough time for early afternoon cocktails

Yo-ho-ho and a...

 

[Chiara’s slave]

F27s are fast, strong and capable boats. My 20kn comment is more about multihull safety and the time to consider reefing than anything else. In 20kn of wind, on a beam reach, he’ll be doing about 17kn, with 32kn apparent wind. Sheet easing time, a few rolls on the main unless experienced. If you’ve reefed at the right time on a F27, you barely slow down, it’s just more controlled, less edgy. I had full sail on ours rounding Bembridge into the solent on our RTI race effort, and ploughed a float right under, hardening up. Scary stuff, though in fact the boat slowed, the rig stalled, out popped the float and we were off again. This is a feature of the design,