End Plate effect of lazy jacks

[lpdsn]

Have you ever quantified the performance loss? If so, how?

The point I made earlier is that you may be able to notice it against another boat in a one to one situation (assuming you can control all the other variables) but on a passage would not make any difference that you could tie down specifically to that.

I have spent a few minutes earlier today trying to find something a bit more definite on the drag of the lines of the lazyjacks but haven't found anything beyond a basic theoretical calculation for a cylinder. I know there was work done based on a conversation with someone who did wind tunnel tests - more in the context of the effect of halyards tied to the toe rail rather than base of the mast, where he said he found the drag of a line was quite significant - but I suspect that was just a final year project. I really wanted to find something empirically based as the surface friction will have a significant effect hence rejecting the theoretical approach. Anyway I don't believe the effect to be trivial.

You only have to sail in a one design fleet for a while to see how much difference boat preparation and a reasonable attention to detail makes. OK it pales besides being unable to trim or steer properly but all these things are accumulative so you can't assume just because you've accepted a hit in one area accepting a hit in another will have no effect. The spread in a one design fleet never ceases to amaze me.

Of course there's always the old argument that it's cruising so it doesn't matter when we get there, but that's personal preference and I'd rather not spend another couple of hours on passage at the end of a long day beating against the tide when I could already have been there before it turned. Others can take the opposite view, or even just decide not to make that particular passage on that day - there are certainly cruising grounds where that choice is easy.

It really is close hauled where the useful force derived from the lift doesn't have a big margin over the drag where unnecessary extra drag has a noticeable effect. A bit of extra drag when beam reaching just doesn't have the same effect.

 

[Robert Wilson]

You only have to sail in a one design fleet for a while to see how much difference boat preparation and a reasonable attention to detail makes. .

Of course there's always the old argument that it's cruising so it doesn't matter when we get there, but that's personal preference and I'd rather not spend another couple of hours on passage at the end of a long day beating against the tide when I could already have been there before it turned. Others can take the opposite view, or even just decide not to make that particular passage on that day - there are certainly cruising grounds where that choice is easy.

It really is close hauled where the useful force derived from the lift doesn't have a big margin over the drag where unnecessary extra drag has a noticeable effect. A bit of extra drag when beam reaching just doesn't have the same effect.

Very interesting points, thank you. I particularly empathise with the "missing the tide" remark. Whether or not adding lazyjacks to Khamsin would seriously P me off remains to be seen, but as earlier posted, even when late, tired and frustrated by the extra drag there is the benefit of downing the sail quickly, tidily and safely thus enabling the tired solo-sailor to get more quickly below to relax with warmth and sustenance!!

Slainte!

 

[Tranona]

Of course there's always the old argument that it's cruising so it doesn't matter when we get there, but that's personal preference and I'd rather not spend another couple of hours on passage at the end of a long day beating against the tide when I could already have been there before it turned. Others can take the opposite view, or even just decide not to make that particular passage on that day - there are certainly cruising grounds where that choice is easy.

That is at the heart of what I am saying. Do you really think that having lazyjacks could make that much difference? Just to put it in perspective I saw some figures the other day (can't remember the reference, but it was an answer to a question in one of the mags) that laminate sails improve speed to windward compared with standard dacron by 0.2 - 0.3 knots at around 5 knots. So a 6 hours passage will take you between 1.2 and 1.8 miles further. A folding prop perhaps a similar saving (although probably not cumulative!).

These are both massive (and expensive!) changes compared with adding lazyjacks and I have difficulty in accepting that on their own there would be any noticeable effect. There are so many variables that affect passage times, particularly where tide and therefore timing is a major factor.

To my mind there are some things that are easy wins - folding/feathering props are easy gains and require no further action to gain benefit, for example; making the boat easy to handle so less demanding; working the external factors such as tides to your advantage etc. However as you work through other things you might change, the potential gains are small and difficult to quantify, plus there is invariably a trade off. That is where I would put lazyjacks - pay off in terms of convenience and ease of handling with maybe a small unquantifiable loss in speed.

Your example of one design fleets is very pertinent. What you are describing is similar to F1 which is also essentially a one design formula. It is true that attention to detail can make the difference between winning and losing simply because of two things. Firstly the race takes place in controlled conditions and secondly the driver needs to have the ability to maximise the use of whatever tiny advantage his car has. Very little connection with driving a car on the roads!

 

[lpdsn]

That is at the heart of what I am saying. Do you really think that having lazyjacks could make that much difference? Just to put it in perspective I saw some figures the other day (can't remember the reference, but it was an answer to a question in one of the mags) that laminate sails improve speed to windward compared with standard dacron by 0.2 - 0.3 knots at around 5 knots. So a 6 hours passage will take you between 1.2 and 1.8 miles further. A folding prop perhaps a similar saving (although probably not cumulative!).

These are both massive (and expensive!) changes compared with adding lazyjacks and I have difficulty in accepting that on their own there would be any noticeable effect. There are so many variables that affect passage times, particularly where tide and therefore timing is a major factor.

I don't think we are disagreeing to a huge extent except in the approach and details. I'd certainly doubt that laminates make only a 0.2 to 0.3Kts difference, for example. The sort of grunt you sometimes put into them to attain the desired sailshape is not something you'd do to even a good Dacron sail if you want to keep it for more than a couple of years, yet those trimming changes can make quite a difference to speed, and perhaps a lot more importantly, to pointing.

As I've said a few times but you've not really picked up on, it's when you are close hauled that all these little things that harm lift and increase drag really have a noticeable effect. It is additive, it can't be anything but, although I'm not niaive enough to assume a linear relationship.

And yes, these losses aren't easily quantifiable in cruising when perhaps the biggest impact you can have on arrival time is deciding which of the crew gets a go on the helm next, but that doesn't mean they don't exist.