Boat speed with different winds speeds and directions

[goat]

Originally Posted by MarkJ

Filthy liar!

My hull speed is 7.96.
Thats was a typo saying 9.96

Sorry

Shouldn't be so hard on him. Most of the time he seems like not a bad guy.
;^)

[Pete7]

For passage planning we use 5 knots and anything above that is a bonus. Although we are the same length, your T31 weighs more and has a long keel which will add drag. If you have a fixed 3 blade prop that's even worse and the equivalent to towing a bucket unfortunately, particularly if its locked with the engine in gear.

Yes you could hit 6 knots on a reach and maintain it if your into 15-20 knots of wind and the seas flat. Driving up and down waves or an ocean swell will take the average speed down. Over 20 knots you are probably looking to reef.

Nice looking boat btw

Have you seen this?

Felicity - Articles

They quote on a long passage so loaded down:

"Felicity is a 1987 Tashiba 31 designed by Bob Perry and built by the Ta Shing yard in Taiwan. She is a heavy double-ender which we have extensively outfitted for long-distance cruising. She makes about 5-6 knots and on an average day can make 120 miles though on our voyage we had many 135-150 mile days and some 60-80 mile days"

[a64pilot]

In all honesty, on a reach in the bay, calm water, zero current. I can run 50% windspeed up to 7.5 kts, the closer I get to hull speed, the more wind it takes, and I'm a heavily loaded full keel Cutter, no racing boat by any means.
I'm tickled pink if I can average 6 kts on passage without running the motor, in truth on just an average 4 to 5 kts is realistic, less than 4 and I crank the Diesel. I know, I'm not a real sailor.
I think the 1/3 windspeed is a little pessimistic

[dakno]

Everything you read here is correct and also of no particular use because everything depends on the conditions on any given day, i.e. wind speed, direction, tides, boat, sails, bottom job, running gear, current, etc.. I have found that you can /will average 5sm hour over 8-12 hr day. Sometimes you are doing 8kts , other times 3.5. If you have distance to cover set a minimum speed of 4kts, when you drop below that its time to motorsail .

Good luck

[dmksails]

Thanks for all the great advice. I found a Polar Diagram for a boat similar to mine - it's exactly what I was looking for.

[roverhi]

FWIW, we averaged 118nm per day through the water for more than 10,000 cruising miles with our 27' water line W32. We used the engine almost exclusively for battery charging with the only long term power, 24hours, to get through totally windless, big roller doldrums. The extremes for daily runs was 12nm on the low end and 178nm on the upper end. The top end was done with winds over 25k on a reach with following seas in the trades. We had the working sails and a reacher/drifter for a sail complement.

Winds are not guaranteed. Nice to know what speed you'll get on a specific point of sail with a given wind but actually totally worthless for planning purposes and, in reality, for the real world of sailing. Even in the trade wind regions, the wind can vary from light in a totally opposite direction to 20k plus from just the right angle. Just pick a figure from the air, PFA, for a planning windspeed and use that. We used 4k or 100nm per day to estimate passage times at sea and it worked fine. If you have a boat with a longer waterline, pick a higher speed. Lower number for a shorter waterline.

If you are looking for a wind/speed relationship to use as a benchmark to optimize the boats performance, get the polars. Still pretty useless as there are so many variables from wave conditions, load of the boat, condition of the sails, etc. that will effect performance.

[zstine]

I see you found polars.... If you want to further explore passage times, enter your polar in a routing program. These routing programs import weather grib files and use your boat's polars to determine the fastest route between start and finish points you selected. qtVlm is a free offline program which is nice if you don't have internet, but if you do, I recommend FastSeas | Weather Routing as this seems easier to use, again free.

luck

[buzzstar]

I think OP has been asking similar questions elsewhere in a brand related group, although if I recall the boat size was different. Identifying polar diagrams seemed to satisfy one aspect of his/her concerns, and then someone said they had posted some which should be available in the archives.

I have found them interesting as a early general reference, but not a useful tool for regular sailing, probably because I am not a racer or even a perfect sailor.

[TheThunderbird]

Right hand thumb says 100nm per day
Left hand thumb may say 80 or 120nm per day , as to weather
Allow for one day off every x days (3-5) and mull over your propensity to crank your engine vs the pleasure of silence.

Sailing is about going to, not arriving at (imo)

[MLOI]

Originally Posted by MarkJ

7.96 knots!

Sorry, typo in my original post that I can't now edit!

My hull speed is 7.96.

Mark

Phew.
A bene 393 was on our shortlist when we bought our current boat. I would have been heart broken if Id chosen a slug when I could have had a rocketship. (I assumed a typo, but it was worth taking the piss)

Last club cruise we went on, we got in close to an hour behind a couple of other boats similar size to our. We had been running deep with 2 reefs in the main and a high aspect jib, which was plenty for the conditions. We probably averaged 6 knots, except for the time spent putting the second reef in.

When I said to one of the other boats that they'd been quick, and asked what sail combo they had up, they replied just a jib.
Long pause as I tried to accept what a crap sailor I am.

Then at last one of them chimed in with "yeah, we motorsailed of course"

Never underestimate the power of the penta in making someones average speed look good.

Mike

[UNCIVILIZED]

As to the 4kts figure, I'm not certain how those suggesting it mean for it to be used. As in many boats, making 4kts VMG to weather can be quite a challenge. Though downwind it perhaps isn't so difficult. So I'd be interested to hear thoughts on how this figure is arrived it. Since without knowing the average winds to be encountered on a passage, who's to say if they'll be cooperative in keeping on sked.

[StuM]

Originally Posted by UNCIVILIZED

As to the 4kts figure, I'm not certain how those suggesting it mean for it to be used. As in many boats, making 4kts VMG to weather can be quite a challenge. Though downwind it perhaps isn't so difficult. So I'd be interested to hear thoughts on how this figure is arrived it. Since without knowing the average winds to be encountered on a passage, who's to say if they'll be cooperative in keeping on sked.

It's useful to have a preliminary planning figure based on averages before you start planning an actual route and timeframe. Obviously it needs to be refined based on prevailing winds for any specific passage.

Of course if you are planning a route directly into or against the trades, you can come up with more appropriate planning speeds, but most passages experience a range of conditions and I find that such an initial planning figure generally ends up close to the actual numbers on longer triips.

[jrbogie]

Originally Posted by dmksails

Hi All -

I've a Tashiba-31 rigged as a cutter. The typical boat speed for this boat is said to be 6 knots. I haven't had a chance to test this as the indicator doesn't work, I'm new to the boat and it is currently 800 miles away and dry docked for the next 3 months. In the mean time I'm practicing navigation and trip planning but I need to know how to estimate speed in order to get elapsed time for my planning.

How would I determine the minimum wind required to get the boat up to 6 knots on a reach. Would it be different when close hauled? Is there a formula for this?

there are many unanswerable questions in sailing much like "how long is a rope?" my guess is by "typical boat speed" for this boat you are referring to the "theoretical hull speed," which is based largely on water line length. any boat will create a bow and stern wave so the longer the water line the longer, and shallower, the waves and a shallow bow wave allows the boat more speed before it must rise over the bow wave onto a plane. more complicated than this but the point is that the theoretical boat speed is of little use to a sailor trying to get the most out of his boat. it's all about sail trim, sail trim, more sail trim and........oh yeah, sail trim, for any given point of sail. and if ever you do hit on a really nice combination and find yourself grooving right along fat dumb and happy, remember that boat speed is like an erection. screw with it and you lose it. did i mention sail trim? happy sails to you.