At last:The real truth about 'performance' saily boats.

[rustybarge]

Hi all,

At last The dark arts of sailing are revealed 'in another place' about the 'real world' speed of performance yachts.

To sum up: an electric trolling outboard of 2 hp would propel a heavy mobo at a faster speed into the wind, than a high performance sailboat which can only make about 2 kts 'speed over the ground' directly to it's destination by the time you take into account the tacking zigzags. And that's on a good day!!!

This is how they calculate their upwind speed against the wind:

.
Originally Posted by Seven Spades
Simple boat speed x COS (bearing difference) Bearing difference is the difference in angle between where you are going and where you want to go. So for example if your destination is way 270 degrees but you can only sail at 310 degrees and you boat speed is 6knts then your effective speed is down to 6 x COS (40) = 6 x 0.766 =4.6knts you can work this out on any mobile phone.
That's useful, thank you. So I'll apply that to my figures above (ignoring lee-bowing the cross-tides):

Sailing at 4.0kts at a bearing difference of 60 deg (50 deg maintainable plus 10 deg leeway):
4 x COS (60) = 4 x 0.5 = 2kts, therefore 30 hours to cross 60NM to Cherbourg.

2. Motorsailing at 5.5 kts at a BD of at least 45 deg (35 deg to wind plus 10 leeway):
5.5 x COS (45) = 5.5 x 0.7 = 4kts appx, therefore 15 unpleasantly wet, heeled and noisy hours to cross

No brainer, then...

http://www.ybw.com/forums/showthrea...to-windward-how-much-more-time-to-allow/page2

30 hrs to do 60 nm at 2kts with the sails, or 15 hrs at 4kts to motor with the saildrive for the same 60 mn.....


No wonder Raggies are so bolshie ......2kts Can you believe it: 2 kts.............

 

[[2068]]

Hmm, but they don't spend all their time going upwind.
A good hull on a broad reach can make good progress.

 

[rustybarge]

Hmm, but they don't spend all their time going upwind.
A good hull on a broad reach can make good progress.

they were actually saying that they don 't even bother trying to sail upwind, most preferring to stay in the marina; that makes a sail boat about as useful as a chocolate tea pot.

it's a bit like a car that can't reverse......

 

[Keen_Ed]

1) Most boats, especially cruiser racers can do better than 4 knots on the wind.

2) I doubt very much that a 2hp trolling motor would make any headway into a breeze when on a boat with any headway.

3) Helming a nicely balanced boat on the wind is just a lovely way to spend a few hours. Really satisfying. Proper sailing.

 

[rustybarge]

1) Most boats, especially cruiser racers can do better than 4 knots on the wind.

2) I doubt very much that a 2hp trolling motor would make any headway into a breeze when on a boat with any headway.

3) Helming a nicely balanced boat on the wind is just a lovely way to spend a few hours. Really satisfying. Proper sailing.

After applying the formula to your better than 4 kts, let's say 4.5 kts...you get 2.2 kts VMG to the destination point.
I have a 6 hp standby OB and can cruise at the breakneck speed of 6 kts in my 1.5 ton Cheetah Powercat: 3 * faster than a snailboat!
Heeled over at 45 deg. taking a cold shower while going very very slowly doesn't sound like much fun to me. :ambivalence:

 

[Keen_Ed]

Well, as has been said on the other thread. If you're cruising and have a choice, you don't go to windward. "Nothing goes to windward like a 747". You wait it out, or go somewhere else. If you don't have a choice, well, HTFU.

If you're racing, then you're racing and nothing else except the race really matters.

 

[rustybarge]

Well, as has been said on the other thread. If you're cruising and have a choice, you don't go to windward. "Nothing goes to windward like a 747". You wait it out, or go somewhere else. If you don't have a choice, well, HTFU.

If you're racing, then you're racing and nothing else except the race really matters.

I read somewhere that a lot of sailboats log more than 50% of their time motoring; Ie: they are really motor sailors, not Raggies.

 

[grumpy_o_g]

After applying the formula to your better than 4 kts, let's say 4.5 kts...you get 2.2 kts VMC to the destination point.
I have a 6 hp standby OB and can cruise at the breakneck speed of 6 kts in my 1.5 ton Cheetah Powercat: 3 * faster than a snailboat!
Heeled over at 45 deg. taking a cold shower while going very very slowly doesn't sound like much fun to me. :ambivalence:

We seem to have suddenly gone from a 2HP trolling motor on a heavy MoBo to a 6HP outboard on a lightweight catamaran?


If heeling over at 45 degrees whilst taking a cold shower doesn't sound like much fun to you then don't do it - I certainly wouldn't. On the other hand I thoroughly enjoy a good thrash to windward and I'm quite happy with an angle of heel up 30 degrees or so if the boat is designed for it. 45 degrees on most boats feels like a knockdown - in reality 20 degrees feels quite well heeled over. This is why sailing boat cockpits look like they do - so you get somewhere to brace your legs if you're sitting up to windward. Like many sailors I usually to prefer to helm from leeward so I like something to lean against whilst looking out under the genoa. Sitting on a powered catamaran sounds like an excellent way of getting from A to B though, which is probably why they're popular with fishermen and ferry operators - it may well be perfect for you too and I hope you enjoy every moment on her.

 

[rustybarge]

We seem to have suddenly gone from a 2HP trolling motor on a heavy MoBo to a 6HP outboard on a lightweight catamaran?


If heeling over at 45 degrees whilst taking a cold shower doesn't sound like much fun to you then don't do it - I certainly wouldn't. On the other hand I thoroughly enjoy a good thrash to windward and I'm quite happy with an angle of heel up 30 degrees or so if the boat is designed for it. 45 degrees on most boats feels like a knockdown - in reality 20 degrees feels quite well heeled over. This is why sailing boat cockpits look like they do - so you get somewhere to brace your legs if you're sitting up to windward. Like many sailors I usually to prefer to helm from leeward so I like something to lean against whilst looking out under the genoa. Sitting on a powered catamaran sounds like an excellent way of getting from A to B though, which is probably why they're popular with fishermen and ferry operators - it may well be perfect for you too and I hope you enjoy every moment on her.

As a mobo owner I never realised that it wasn't possible to sail at a useful speed to windward in a sailboat.
Please excuse my ignorance, but say in a 20 kts headwind how fast could a close hauled 12 mtr yacht go?

 

[grumpy_o_g]

As a mobo owner I never realised that it wasn't possible to sail at a useful speed to windward in a sailboat.
Please excuse my ignorance, but say in a 20 kts headwind how fast could a close hauled 12 mtr yacht go?

It depends entirely on what you call a useful speed really but sailing is very much about the journey rather than the arrival. Interesting you say 12 meters; most sailors would think of an Americas Cup boat when you say that but they weren't anything like 12 meters loa and bore as much resemblance to a typical yacht as a Formula One car does to a Ford Focus...

A fast 35-40 foot cruiser-racer with a good crew could make 7 or 8 knots through the water if well-sailed in a good wind with reasonable seas. Something like a Dragonfly 35 trimaran could manage double figures just I guess. Most yachts would be around 5 or 6 knots at best though. A good cruiser of that size will make 4 knots or so to windward in my experience and a very slow one may simply not go to windward at all - if it can't make at least 3 or 4 knots in ideal conditions it really isn't a sailing boat to me, it's motor-sailor. Sailors are wary of lee shores for good reason but the sea state plays as big a part as wind strength. the fastest boats are the lightest and often the beamiest too but they can sometimes end up getting stopped by a steep and nasty sea every time they hit a wave - that is not just uncomfortable but can also really slow the boat down.

I've done 50 or 60 mile passages to windward (absolutely nothing to some on here, who have crossed the Atlantic the wrong way) and enjoyed every minute I was awake but it is a different mindset. If you want a cup of tea then have one - go and make a butty if you want. If you're off watch get some kip, read a book or whatever. You will be at sea for hours and you learn to work with the boat rather than against it. It really throws me when the tide or something changes the way the boat's moving. If you focus on how fast you're covering ground in absolute time you'll go round the bend. Instead you enjoy getting the best out of the boat, chatting and bantering with each other, trying to use the conditions (wind, tide, forecasts, etc) to your advantage. Get it right and it's a glorious feeling, get it wrong and you learn from it.

Sometimes it becomes more about keeping going or even survival, other times you just say bugger this for a game of soldiers and put the motor on until you get somewhere - it depends on the crew. I'm lucky in that I usually sail with like-minded folk so the engine doesn't go on unless there's no wind or we can't make ground against the current (unless we need to get back from an evening sail perhaps). It's a bit different if you have a partner and kids who really aren't into it so much - that's one reason why I charter rather than own a boat. Isn't that much cheaper but the sailing I got with my other half was in warmer climes and suited her. She wouldn't have enjoyed it if it was a brisk, showery day in Solent going to places she can visit every day by car.

 

[rustybarge]

. It depends entirely on what you call a useful speed really but sailing is very much about the journey rather than the arrival. Interesting you say 12 meters; most sailors would think of an Americas Cup boat when you say that but they weren't anything like 12 meters loa and bore as much resemblance to a typical yacht as a Formula One car does to a Ford Focus...

A fast 35-40 foot cruiser-racer with a good crew could make 7 or 8 knots through the water if well-sailed in a good wind with reasonable seas. Something like a Dragonfly 35 trimaran could manage double figures just I guess. Most yachts would be around 5 or 6 knots at best though. A good cruiser of that size will make 4 knots or so to windward.

Here's a comparison test:

Hi tech carbon fibre racer/cruiser at £400k : 3.5 to 4 kts Progress upwind (VMG) to destination, but only in good conditions.
My manky 40 year old 13' dory with 2.5 Yamaha outboard £400: 4 kts into the wind at full chat(wot).

At last I understand what the elephant in the room is; a sailboat cannot sail into the wind fast enough to make any decent progress. A motor sailer with a decent sized engine (100hp?) would make better sense; just motor upwind......

a trawler yacht with a small mast and flappy things 'just to sail down wind' suddenly becomes a good way of saving massive amounts of fuel on a long trip, if you are happy cruising at hull speed (6 or 7 kts?).


The ultimate displacement trawler with sails.......?

 

[Lozzer]

Rusty..... what a load of rubbish

To think a 400k tricked up sailing yacht would only make 3.5 - 4 knots upwind is ludicrous. A lot of the formulas used to calculate speed are out of date when applied to modern designs. I would have a wager that says your dory would not win the race that you describe.

Also a big advantage the sailing boat has is it doesn't have to stop every x miles for fuel..

We can all make comparisons to discredit, as a professional skipper of motor and sailing yachts I can make either case. Interesting to know the point of your thread?

 

[Resolution]

As a mobo owner I never realised that it wasn't possible to sail at a useful speed to windward in a sailboat.
Please excuse my ignorance, but say in a 20 kts headwind how fast could a close hauled 12 mtr yacht go?

I have a 13 metre cruising yacht and I do my distance passage planning with an average speed of 5 or 6 knots. This is based on wind speeds ranging from zero(when we do motor) to 30 knots. Above that we try to keep in harbour. And of course winds from dead ahead (when VMG will be low) to lovely beam reaches (when we can average 8 to 10 knots).

You haven't discussed how long you spend re-fuelling. Not something we do very often.

Nor have you discussed the effect of waves on speed. At what wave size/shape does your mobo slam itself to bits?

In conclusion, we are comparing apples and oranges here. Sometimes one is nicer than the other. Both can be enjoyable, and we should be glad of that.

 

[rustybarge]

Rusty..... what a load of rubbish

To think a 400k tricked up sailing yacht would only make 3.5 - 4 knots upwind is ludicrous. A lot of the formulas used to calculate speed are out of date when applied to modern designs. I would have a wager that says your dory would not win the race that you describe.

Also a big advantage the sailing boat has is it doesn't have to stop every x miles for fuel..

We can all make comparisons to discredit, as a professional skipper of motor and sailing yachts I can make either case. Interesting to know the point of your thread?

As a mobo owner I had no comprehension of the dynamics of a sailing boat, I always presumed that a yacht could make as good progress upwind as it did downwind ( obviously not as fast!), so in a moment of 'enlightenment' when I read the thread about sailing upwind I suddenly realised that sailing Boats CANNOT make good progress into the wind at all; hence they are all equipped with motors/ saildrives.

In conclusion:
Ques: what don't they tell you about sailboats ?
Ans: they can't sail into the wind! You're going to need an engine.

Same Q for mobo's:
Ques: what don't they tell you about mobo's?
Ans: A 40' planing mobo will probably only manage 1 mpg, or €700 in diesel for every 100 nm!

 

[rustybarge]

I have a 13 metre cruising yacht and I do my distance passage planning with an average speed of 5 or 6 knots. This is based on wind speeds ranging from zero(when we do motor) to 30 knots. Above that we try to keep in harbour. And of course winds from dead ahead (when VMG will be low) to lovely beam reaches (when we can average 8 to 10 knots).

You haven't discussed how long you spend re-fuelling. Not something we do very often.

Nor have you discussed the effect of waves on speed. At what wave size/shape does your mobo slam itself to bits?

In conclusion, we are comparing apples and oranges here. Sometimes one is nicer than the other. Both can be enjoyable, and we should be glad of that.

......that's why I suggested a sail assisted trawler yacht would be the best compromise; it would cruise downwind at hull speed under sail power like the square riggers, and do OK on a beam reach; fire up the engine to cruise to windward.

 

[Lozzer]

No no no

This trawler type boat is no use for anything unless the engine is on except for trawling that is.. They simply are not designed to sail on any angle the name gives you a massive clue.


Your QA I dont understand.

Sailing boats do go to windward but not directly. The wind angle is all down to design. Simple physics lessons teaches us this no reading forums like this. Venturi effect...

Anyone with half a brain cell could work out that pushing 30 ton through water will be an expensive thing to do.

700 euro for 100 miles is cheap, if i open the taps on the mobo I skipper we would be burning circa 3000 litres do do 100 miles. at 1.35 euro per litre you do the sums

 

[rustybarge]

No no no

This trawler type boat is no use for anything unless the engine is on except for trawling that is.. They simply are not designed to sail on any angle the name gives you a massive clue.


Your QA I dont understand.

Sailing boats do go to windward but not directly. The wind angle is all down to design. Simple physics lessons teaches us this no reading forums like this. Venturi effect...

Anyone with half a brain cell could work out that pushing 30 ton through water will be an expensive thing to do.

700 euro for 100 miles is cheap, if i open the taps on the mobo I skipper we would be burning circa 3000 litres do do 100 miles. at 1.35 euro per litre you do the sums

hmmm, let's see.
66 gals per mile, not as big as a large cruise ship that uses 1/2 ton per mile, Not as small as a 80' twin 1200hp that uses 66 gals hour at 25 kts....................

100 mtr coaster?

 

[Tranona]

As a mobo owner I had no comprehension of the dynamics of a sailing boat, I always presumed that a yacht could make as good progress upwind as it did downwind ( obviously not as fast!), so in a moment of 'enlightenment' when I read the thread about sailing upwind I suddenly realised that sailing Boats CANNOT make good progress into the wind at all; hence they are all equipped with motors/ saildrives.

In conclusion:
Ques: what don't they tell you about sailboats ?
Ans: they can't sail into the wind! You're going to need an engine.

Same Q for mobo's:
Ques: what don't they tell you about mobo's?
Ans: A 40' planing mobo will probably only manage 1 mpg, or €700 in diesel for every 100 nm!

I just love the way you wallow in your own ignorance!. Nobody is hiding anything - the only failure is yours in not understanding physics. Boats have been sailing all over the world for thousands of years just using the wind and in the full knowledge of the limitations. Speed is relative and with a displacement boat of the size we are talking about is limited to a range of somewhere between 5 and 7 knots. However the ability to achieve this depends on harnessing the power of the wind through the sails. The more the wind the greater the potential power. However that power has to be converted into forward drive and the closer you get to the wind the less drive you can extract. Quite possible to achieve maximum hull speed at between 30-40 degrees from the wind but as you cannot go direct to the wind the speed over the ground towards a point to windward is lower.

Nothing difficult to understand about this, so the skill is in shaping a course and exploiting what you have in the way of power to maximise your progress. The alternative is to abandon use of the wind as your source of power and use the engine, or use a combination of the two. As others have explained that choice will depend on a number of factors and also on the specific characteristics of the boat you have. At one end of the spectrum you might have a yacht designed to maximise speed to windward where the engine is an auxiliary, and likely to be rather ineffective because of low power and at the other end your sail assisted trawler where the prime motive force is the engine and sails are just a partial substitute when the wind is on the beam.

Comparing a boat that depends primarily on the wind for power and one that has only engine for power is a pointless exercise. They are fundamentally different.

 

[rustybarge]

. I just love the way you wallow in your own ignorance!. Nobody is hiding anything - the only failure is yours in not understanding physics. Boats have been sailing all over the world for thousands of years just using the wind and in the full knowledge of the limitations.

Downwind on the prevailing trade winds.........

However that power has to be converted into forward drive and the closer you get to the wind the less drive you can extract. Quite.

...just like I was saying, a sail boat is useless at sailing to windward.

. Comparing a boat that depends primarily on the wind for power and one that has only engine for power is a pointless exercise. They are fundamentally different

.....why do sailboats have engines if this is the case?

 

[Lozzer]

hmmm, let's see.
66 gals per mile, not as big as a large cruise ship that uses 1/2 ton per mile, Not as small as a 80' twin 1200hp that uses 66 gals hour at 25 kts....................

100 mtr coaster?

What are these numbers? 800 lph = 175 gal 100 miles = 1.75gal per mile this is from 2 x CAT C32 1925HP engines on 85 ton mobo