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Discussion Starter #1 (Edited)
Hi, we're currently planning an extended cruise, possibly england -> brazil, and are trying to determine what a conservative figure for average daily run would be. Our boat is a heavy 25 foot steel boat, sail area, approx 350 sq. feet.
Does anyone know of a source for daily run data to give an idea what we should be planning for?
It would be most usefull if it also give the data for that boat such as sail area, displacement length, so that a meaningful comparison can be made?

Many thanks,

Chris
 

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Hi Chris, please go here CLICK

You can compare your boat with similar boats. And if you don't find your boat like that you can add it there.

It's going to be a really really large passage on your boat..you're leaving from England? have you decided on a route yet?

You will, in a boat like that, probably average 4 to 6 knots, with some 11 knot peaks on waves. That is a looong pasage indeed...visit Portugal...it's wonderfull


Good luck...
 

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Discussion Starter #3
Thanks Guilietta, but I can see my request wasn't all that clear. What I'm specifically after is details of what some boats average daily runs are.

The data such as their length/beam/displacement/sail area was just so I could make a meaningful comparison to boat similar to mine.

Our boat is a Tom Thumb 24, which comes out with a hull speed of 6.3 knots, and sail area to displacement ratio of 15.33.

Thanks again,

Chris
 

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Discussion Starter #4
I'm too junior to be able to post a link to our proposed route! But it goes something like:

England
Canaries
Recife Brazil
.......lots of brazil....
Down to Uraguay
Up to carribean
Back to england

Looking at something like 2 years.
Our current speed plucked out of thin air for planning is 3.5 knots, which would give daily runs of 84 miles.
 

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Well it depends on the boat, crew, conditions, etc.

I average around 10 knots, sometimes a bit more, sometimes less. Normaly for me, where I sail, and when I cruise or ferry the boat, I allways calculate ETA based on 10 miles in one hour, and so far..right on...

in fact lately I have done more than 10 miles/hour.
 

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Discussion Starter #7
Cascais looks quite convenient to our route...so may well do, thanks for the kind offer :)

Wow 10 knots average! - that will be a figure definately beyond our dreams in our small boat !
 

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Chibb,

not aware of any site or resource that would give this info. Best I can offer is The Voygager's Handbook by Beth Leonard gives 120-125 NM for a 40ft "traditional" yacht, which would be a "heavy" yacht. This average worked out as 67-72% of the hull speed.

Your boat would get no where near these average runs. Based on your hull speed of 6.3kts and if you could get the same percentages your average would be 4.2 to 4.5 knots, or an average daily run of 100 to 108NM.

The other thing to do is start measuring all your coastal passages and see what your average speed is. Then take a bit off for night sailing, which will probalby be slower.

have fun, Ilenart
 

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Discussion Starter #9
Thanks Ilenart, I've got the book, will find that section now. Sounds like a useful guestimate
 

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Our current speed plucked out of thin air for planning is 3.5 knots, which would give daily runs of 84 miles.
That sounds like a good conservative figure. If you get there faster, so be it.

Canaries to Brazil is a bit over 2,600NM, or a 31 day passage based on your stats. Sounds like fun!

Ilenart
 

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Your estimate seems reasonable

Our current speed plucked out of thin air for planning is 3.5 knots, which would give daily runs of 84 miles.
With a 27 foot waterline I used 100 miles for planning purposes and generally did a bit better. I think your estimate makes sense. What you will actually do depends on factors like what wind belt you are in. In the trades on a broad reach you will do better, reliably day after day. In the Westerlies every day can be different. Another factor is how much you can/want to motor on windless days.

I think it is better to be conservative in your estimate than the reverse. If you get somewhere a bit early you have more time to explore. If your planning it so ambitious you will spend all your time playing catch-up and not enjoy it nearly as much.
 

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Hi, we're currently planning an extended cruise, possibly england -> brazil, and are trying to determine what a conservative figure for average daily run would be. Our boat is a heavy 25 foot steel boat, sail area, approx 350 sq. feet.
Does anyone know of a source for daily run data to give an idea what we should be planning for?
Average daily runs are meaningless until after you have arrived at your destination. Based on reported "Average daily runs" we expected our crossing to take 26 to 30 days, not the actual 55 days. I'm guessing your boat is not a great light air sailer. I'd plan for any voyage to last three times longer than reported averages.



This is what it looked like for four days. That is 0.0 MPH just 120 miles from our projected landfall. We eventually drifted close enough to be within motoring range. My boat is faster than yours BTW. :cool:
 

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Our current speed plucked out of thin air for planning is 3.5 knots, which would give daily runs of 84 miles.
Chibb,

That sounds about right, maybe a bit optimistic. I know the Roberts Tom Thumb boat design is a stout vessel, she'll take care of you, but I would not expect any great turn of speed from her especially passing through the doldrums.

Not trying to discourage you, just want to make sure you provision adequate food and water for the longer legs of the trip. Hopefully you'll make better runs and have more time to spend at your destinations!

P.S. For those unfamiliar with this design, it is similar to the PSC Dana 24, but usually in steel and a bit larger. Neat little boats:

Tom Thumb
 

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Never having crossed an ocean on a sailboat yet, wouldn't it be good to have some fuel for that outboard so you could motor until you found wind? As Vega points out, zero knots does nasty things to an average speed, and you could run the outboard at a slow, effficient rpm. I would think that adding some fuel bladders (and jerry cans) would decrease the amount of food and water needed, and therefore make a reasonable trade-off.

But like I said, I haven't sailed across an ocean yet.
 

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Never having crossed an ocean on a sailboat yet, wouldn't it be good to have some fuel for that outboard so you could motor until you found wind? As Vega points out, zero knots does nasty things to an average speed, and you could run the outboard at a slow, effficient rpm. I would think that adding some fuel bladders (and jerry cans) would decrease the amount of food and water needed, and therefore make a reasonable trade-off.

But like I said, I haven't sailed across an ocean yet.
Bene,

The conventional thinking is that the distances we're talking about on an ocean voyage are so long that motoring for a half a day or more would not make much difference, wind-wise. With an outboard, you would go through A LOT of fuel in 24 hours of motoring. Best to save it for when it's really needed (landfall) and wait for the wind to come to you.

At least, that is the usual thinking in small boats like these. But even many larger boats on longer passages adopt the same philosophy. On a boat your size for instance, you'd probably burn close to a gallon an hour, which would consume quite a bit of your reserves during a 2-3 day windless stretch on a 3-4 week Pacific passage.
 

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Discussion Starter #20
Chibb,

That sounds about right, maybe a bit optimistic. I know the Roberts Tom Thumb boat design is a stout vessel, she'll take care of you, but I would not expect any great turn of speed from her especially passing through the doldrums.

Yes, we've done a reasonable amount of sailing in F4/5 in her and she goes along nicely at 5/6 knots, but haven't done much at all in the lighter stuff. Thinking of having twin running headsails (twizzle rig). One hanked on, one free flying (wire luff) to give around 400 sq foot area.
 
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