May I ask a stupid question about my boat?

[yukonbob]

I think I got some good info from Tomfoolery on tacking and yukonbob about losing about a half a knot when he points too high into the wind.

Boat: in 20knts of wind pointed 35- 40 degrees off true wind I don't lose .5 knts I can can only do .5-1.5knts. I'm with Ixneigh in that if I can't get at least 3.5 I fall off until I can, which at 7-15knts of true wind is about 45 degrees with 4.5-6.5 knts of speed. That extra 5 degrees into those same wind conditions usually sees a 50% speed reduction so 1.5-3 knts. Increase the wind and it slows down even more, which I believe has more to do with the light weight and higher windage. Sailing down Taiya inlet which is 14nm long and about 2nm wide with 6000 mountains on both sides, the wind comes straight up it from the south. When I sail upwind with newer sails, full main and 105% jib my tacks are almost perfect 45's. I've done what I think you're trying to do (make more headway at slower speeds then get on a reach to try and make up some speed/time)? If that's what you're getting at? I myself would and do prefer to sail at a faster speed making more tacks and spend more time sailing IMO it's funner and makes for a more comfortable ride in choppier waters.

[BOAT]

I think I got some good info from Tomfoolery on tacking and yukonbob about losing about a half a knot when he points too high into the wind.

Boat: in 20knts of wind pointed 35- 40 degrees off true wind I don't lose .5 knts I can can only do .5-1.5knts. I'm with Ixneigh in that if I can't get at least 3.5 I fall off until I can, which at 7-15knts of true wind is about 45 degrees with 4.5-6.5 knts of speed. That extra 5 degrees into those same wind conditions usually sees a 50% speed reduction so 1.5-3 knts. Increase the wind and it slows down even more, which I believe has more to do with the light weight and higher windage. Sailing down Taiya inlet which is 14nm long and about 2nm wide with 6000 mountains on both sides, the wind comes straight up it from the south. When I sail upwind with newer sails, full main and 105% jib my tacks are almost perfect 45's. I've done what I think you're trying to do (make more headway at slower speeds then get on a reach to try and make up some speed/time)? If that's what you're getting at? I myself would and do prefer to sail at a faster speed making more tacks and spend more time sailing IMO it's funner and makes for a more comfortable ride in choppier waters.

That's good info bob - it makes sense too that your real point is closer to 45 degrees. I think that is the magic number I am looking for and that's what the software says but in real life I think it may be closer to 50 degrees. If the 50 degree angle is right, it means the whole tacking plan needs to be rethought - I don't think the back and forth zig zag is the most efficient route once you depart the 45 degree standard. I could be wrong - but that's what I am trying to figure out here. This issue of tacking more than 45 degrees is a problem I have visited before with the A23 that Tom accurately identified.

Wow. That's a clean Aquarius 23!
But then, I guess it was nearly new at that time.

Yuppers - you can be sure they don't look like that now. Number 276 was built in 1969 I think based on that sail number - the other one I can't see the number; it's the Russel boat, I don't know the year built but I knew the skipper well - He was a writer for SAIL magazine:

Back then the trailer sailboat thing was an oddity that all the periodicals wanted to know about so when they got wind of an expedition to the Sea of Cortez they were all over it along with some other publications. I was on a blue 23 considered one of the heaviest in the fleet with a custom interior. When many skippers were stripping their boats of weight even removing their motors my dad had the thought of going out heavy full of food water and canned goods all close to the floor. It worked; we got a 4th place that day.

Conditions were primitive in Mexico back then so landing with a heavy boat had it's own issues as I found being on the front of the bow line in this picture:

That was when we and others started to realize added weight could make these 'high ballast' boats faster in heavy wind (as Highlander has already proven). In light winds though it will make you a slug. Did I mention it makes it difficult to land the boat too?:

That was then and this is now. These-days, we trailer people are considered passe' and looked down upon at the San Diego Yacht Club and sailboat anarchist website (or whatever they call it), but it was not like that back in the beginning - in the early days we were considered skilled and an alternative to the polo shirt crowd - we were actually considered the superior sailors back then because we could manage these unbalanced lightweight crafts and because we went places the keelboats did not. (I mean really, ANYONE can sail a Beneteau) but not everyone can sail a sabot.
So be it.
As then. I still am not ashamed of the performance characteristics of my trailer boat - if it's 50 degrees, so be it - but that means I'm not going to use the tack plan of a skipper that can point 35 degrees.

[NiceAft]

BOAT,

I'm confused about something.

This island is 200 miles away, so you can't sail there in one continuous sail without either being sleep deprived or using the auto pilot. If you use auto pilot, then why the concern over the most efficient tack? Is there maybe a crew involved?

Look, I may be completely wrong, and I am most definitely not in any way trying to pressure you. I am just trying to figure out the intensity of you inquiry. Maybe it's just an academic challenge on your part. You have certainly piqued the interest of many of us.

It seems between Catagail and Yukonbob, the answer to your conundrum appeared. . Now what

Ray

[Jimmyt]

Out of curiosity, 200 miles at what heading? What is the wind direction? Trying to get a picture of what you're up against. In abstract, the problem doesn't seem very easy to attack. Maybe some details would help. Looks like an interesting exercise...

[yukonbob]

If your using the furler check for forestay tension, boats will never point with a sloppy forestay, I find that somewhat of an issue with the CDI furler, its very hard to get reasonable tension.

How can you measure the tension on a CDI furler? And what should it be?

I decided to loosen the rig a little this year (had it a little tight last year) to help reduce weather helm. It will be interesting to see how that will effect my upwind performance.

[yukonbob]

Out of curiosity, 200 miles at what heading? What is the wind direction? Trying to get a picture of what you're up against. In abstract, the problem doesn't seem very easy to attack. Maybe some details would help. Looks like an interesting exercise...

Ya Boat! There had better be room for good video cam on board when you do it

[seahouse]

If your using the furler check for forestay tension, boats will never point with a sloppy forestay, I find that somewhat of an issue with the CDI furler, its very hard to get reasonable tension.

How can you measure the tension on a CDI furler? And what should it be?

The tension on the forestay on an "M" is determined by the factory design of the rigging to be a certain constant ratio relative to the top (outer) shrouds. Because of this the tension in the top shrouds (which can more easily be measured than the forestay tension once the furler is installed) can be set and the forestay tension will then be correct.

The ideal way to set the tension is to measure the elongation of the shroud as the tension is applied.

More commonly a Loos Gauge is used that measures the tension and it then gets set as a percentage of the breaking load of the wire, somewhere between 10 and 25%.

I use around 200 lbs for the top shrouds on my boat. Using the mast raiser to judge that, I have found that if you apply the maximum force that the raiser can apply before failure (or before you think it is about to fail) and can just engage the forestay pin at the bow, then your tension will end up about there when the mast raiser tension is removed.

- Brian.

On edit - I would expect that an "X" would be similar to an "M" .

[BOAT]

BOAT,
If you use auto pilot, then why the concern over the most efficient tack?
Ray

Because I need to know when to wake up and make my turn.
If we were talking 800 miles or more here your question would be correct as there would be no need to wake up. On our old boats getting 100 miles in a 24 hour period was considered a great days and really fast. The M boat can easily cover over 100 miles in one day - so for a 200 mile leg your going to make some turns if your going upwind.

BOAT,
It seems between Catagail and Yukonbob, the answer to your conundrum appeared. . Now what
Ray

Now I work out a tack plan for the M at 50 degrees.
I can automate my software to make the most efficient course legs to cover the distance involved in the fastest way based on speed. Speed determines how many turns to make based on an angle.
And yes, the problem is theoretical as an exercise in math but it's also a very practical tool that will provide a guide to calculate the turns that will result in the most efficient tack plan, (the plan that gets me there the fastest).

You can buy software that does this on the fly - the Americas Cup guys have been using it for many years. I looked at some of the software and it gave tack plans I did not think my boat could execute. The software is self correcting, but that's not good enough for me - I want something that works for 'boat' so I know right up front how many miles I will covering BEFORE I cover it! So I have been using excel spreadsheets and plugging in speed and angles to get tack info and distance traveled - but it's cumbersome and not sufficiently tested because I need to go over 100 miles with a wind instrument to confirm my numbers.

I just thought you guys might already know the number. I guess I will just need to go out there and run the numbers on the water, (or wait till I retire and have the time).

[sailboatmike]

I would think that it would all be theoretical, you can do all the maths but at the end of the day if the wind shifts a few degrees it will send all your maths up the creek and one would need to take tides and currents into consideration and the wind speed would need to be constant to make it a practical.

[BOAT]

I would think that it would all be theoretical, you can do all the maths but at the end of the day if the wind shifts a few degrees it will send all your maths up the creek and one would need to take tides and currents into consideration and the wind speed would need to be constant to make it a practical.

Yes, that's why the software - it's dynamic - the idea is to send the devicenet data directly from the plotter and wind instrument to the software (spreadsheet) and every 4 or 5 minutes the spreadsheet automatically re-calculates a new heading that can be sent back to the plotter. All the thing really does is send a new set of waypoints - the destination remains the same but the waypoints become your turns. That's how my plotter works - it receives waypoints from most any device.

[March]

sailboatmike wrote:
I would think that it would all be theoretical, you can do all the maths but at the end of the day if the wind shifts a few degrees it will send all your maths up the creek

It's like flying by the seat of your pants, as it were. On a plane, the pilot might choose to fly by the instruments (something BOAT seems to be attempting to do...) or use dead reckoning and fly what he sees, making constant, minute adjustments as warranted.

The problem may still be academic, as suggested above. You choose a course and make T time, right? You will never know how much faster (or slower) you might have gone if you had chosen a different course. Sure, you may speculate all you want and try to do better next time, but next time the conditions will be different. You will never find yourself in the same waters, wind, currents, situation, to make a valid and meaningful comparison between the results.

The thing that works best seems to be to develop a sense of sailing by the seat of your pants, with every new experience. You would probably learn more from that than gathering meaningful data and attempting to match them by setting a course "mechanically"

[NiceAft]

As I said a whole lot earlier, sailing is a Zen thing; it's the journey, not the destination

Ray

[bobbob]

If your using the furler check for forestay tension, boats will never point with a sloppy forestay, I find that somewhat of an issue with the CDI furler, its very hard to get reasonable tension.

How can you measure the tension on a CDI furler? And what should it be?

The tension on the forestay on an "M" is determined by the factory design of the rigging to be a certain constant ratio relative to the top (outer) shrouds. Because of this the tension in the top shrouds (which can more easily be measured than the forestay tension once the furler is installed) can be set and the forestay tension will then be correct.

The ideal way to set the tension is to measure the elongation of the shroud as the tension is applied.

More commonly a Loos Gauge is used that measures the tension and it then gets set as a percentage of the breaking load of the wire, somewhere between 10 and 25%.

I use around 200 lbs for the top shrouds on my boat. Using the mast raiser to judge that, I have found that if you apply the maximum force that the raiser can apply before failure (or before you think it is about to fail) and can just engage the forestay pin at the bow, then your tension will end up about there when the mast raiser tension is removed.

- Brian.

On edit - I would expect that an "X" would be similar to an "M" .

I get how you measure the tension on a stay or a shroud - but how would you measure the tension on a furler?

[seahouse]

I get how you measure the tension on a stay or a shroud - but how would you measure the tension on a furler?

The forestay runs within the foil on the CDI furler. It is the tension on the forestay and not the furler foil itself (which, being a solid piece would need little tension, relative to the tension on the stay, to keep it straight) that would have the greatest effect on the pointing ability of the boat, assuming the tension on the genoa or jib uphaul were correct for the sail.

I think that is what was meant by the original question.

All that also assuming you are not being facetious with the last question.

[seahouse]

sailboatmike wrote:
I would think that it would all be theoretical, you can do all the maths but at the end of the day if the wind shifts a few degrees it will send all your maths up the creek

It's like flying by the seat of your pants, as it were. On a plane, the pilot might choose to fly by the instruments (something BOAT seems to be attempting to do...) or use dead reckoning and fly what he sees, making constant, minute adjustments as warranted.

The problem may still be academic, as suggested above. You choose a course and make T time, right? You will never know how much faster (or slower) you might have gone if you had chosen a different course. Sure, you may speculate all you want and try to do better next time, but next time the conditions will be different. You will never find yourself in the same waters, wind, currents, situation, to make a valid and meaningful comparison between the results.

The thing that works best seems to be to develop a sense of sailing by the seat of your pants, with every new experience. You would probably learn more from that than gathering meaningful data and attempting to match them by setting a course "mechanically"

I think BOAT already has the seat of the pants sailing part down pat, better than most. And is now taking that to the next level by this thread, and not the other way around...