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Peter Barton View Drop Down
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    Posted: 10 Sep 20 at 3:46pm
Originally posted by Paramedic

Originally posted by Peter Barton

 
Surely the ability of a hull to carry weight is more a function of the hull design shape and size rather than its weight. Ultimately it is the all up total weight (boat + sailor) that needs to be considered in terms off 'carrying' ability.
'Overpowering' is not an issue until the breeze is up and a heavier sailor is then more able to deal with that. Before then the extra power does help with initiating speed and acceleration.


So, your boat weights say 50 kilos. we have a hobbit helm who also weighs 50 kilos. We also have a helm who weighs 75 kilos. He is sailing at a 25% weight disadvantage.

Let's take a boat that weighs 75 kilos. and the same two helms. The heavier helm now has a 17.75% disadvantage by my (very quick, please forgive me if i'm wrong) maths.

Thats one reason why the lighter a boat is the harder it is to make it carry weight. Your variable (crew) weight is a larger portion of the whole package and it can be reduced easily and legally by changing the sailor. I think its more of a problem for two person boats, but it must also apply here.


Understood. I was considering the ability of the design shape to carry extra weight and you are considering the increased proportional difference's effect on equality.

You are suggesting the extra weight is a disadvantage though, I would suggest that a good proportion of the time it is not. 
In the middle ground there is a whole load of interesting racing with the heavier sailor trying to gain more upwind than he might lose downwind......What are the downwind angles? Is it marginal planing or blast reaching? Will the lighter sailor be able to make a comeback downwind through traffic? Wind with tide or against? Waves or not?
Those weight differences playing out into an overall result, especially over a long series, are really restricted to similar good ability sailors in boat speed prioritised conditions. Otherwise many other race variables and skills will be the deciding factor.

Personally, having experienced it, I will always take the 50kg all up weight boat over the 75kg one, thanks. I have never felt the urge to suggest that all RS Aero sailors add 25kg to their boats so that they can reduce that proportional difference and have more momentum to push though waves rather than popping agilely over and around them.

If a boat could could be made at 0kg all up weight I would be at the front of that queue. It would be like a non foiling foiler - weightless! I could tie it down to a ballasted trolley when ashore and be sure to hook myself to the end of the mainsheet when afloat to avoid ever losing it.


Edited by Peter Barton - 10 Sep 20 at 4:34pm
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Peter Barton View Drop Down
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Posts: 129 		Post Options Post Options   Quote Peter Barton Quote  Post ReplyReply Direct Link To This Post Posted: 10 Sep 20 at 4:01pm
Originally posted by Neptune

At our club all boats get to choose their rig, but their handicap is always based upon the fastest PY, I think that keeps people sailing longer and also stops bandits swapping up at the lower extreme

Yes, we have similar locally. The flexible rig rule was there for the Lasers before the RS Aeros arrived. Except we only allow changing down as changing up would then effect previous results if you adjust all those handicaps to the faster one.
However, in reality, with the exception of the series leaders, those with a choice option sail each race for the enjoyment of that race alone,  rather than a with focus on the whole series. So they just have a new series with a new rig. 
The flexibility helps participation (travelling, starting and finishing races), safety (not over canvassed) and enjoyment (of appropriate sized rig).
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Peter Barton View Drop Down
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Posts: 129 		Post Options Post Options   Quote Peter Barton Quote  Post ReplyReply Direct Link To This Post Posted: 10 Sep 20 at 4:29pm
Originally posted by turnturtle

....the multiple rigs (or certainly between the 7 & 9) do not 'add value' imho.  No harm in this, the Aero's a cracking success and nice to see it building fleets around the UK.

I would have to disagree sorry, based on my enjoyment of sailing both the RS Aero 7 and RS Aero 9 similar amounts over the last 6 years.
It adds a lot of interest, keeps me in the right power range when I choose to be and sometimes I don't chose to be. The rigs are so similar and everything else remains unchanged, so the simplicity of the RS Aero does not suffer and it all fits nicely in the bags under the cover for storage and transport. With alternating two rigs the sails then last much longer too, especially the RS Aero 9 if (unlike me) you mainly use it in lighter winds. You just have options and most keen RS Aero owners choose to exercise that flexibility with a 2nd rig to achieve more good sailing days at each end of the spectrum.

I understand RS are offering a 25% discount off a 2nd rig with new RS Aeros at the Southampton boat show starting tomorrow....
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Paramedic View Drop Down
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Posts: 929 		Post Options Post Options   Quote Paramedic Quote  Post ReplyReply Direct Link To This Post Posted: 10 Sep 20 at 8:11pm
Does that mean you get a 5 instead of a 7?

Edited by Paramedic - 10 Sep 20 at 8:11pm
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Rupert View Drop Down
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Posts: 8956 		Post Options Post Options   Quote Rupert Quote  Post ReplyReply Direct Link To This Post Posted: 10 Sep 20 at 8:46pm
Originally posted by Paramedic


Does that mean you get a 5 instead of a 7?


A 5.25 rig, I think!
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Paramedic View Drop Down
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Posts: 929 		Post Options Post Options   Quote Paramedic Quote  Post ReplyReply Direct Link To This Post Posted: 10 Sep 20 at 9:07pm
Originally posted by Rupert

Originally posted by Paramedic


Does that mean you get a 5 instead of a 7?


A 5.25 rig, I think!

inc VAT  LOL
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turnturtle View Drop Down
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Posts: 2538 		Post Options Post Options   Quote turnturtle Quote  Post ReplyReply Direct Link To This Post Posted: 11 Sep 20 at 11:47am
Originally posted by Peter Barton


Originally posted by turnturtle

....the multiple rigs (or certainly between the 7 & 9) do not 'add value' imho.  No harm in this, the Aero's a cracking success and nice to see it building fleets around the UK.

I would have to disagree sorry, based on my enjoyment of sailing both the RS Aero 7 and RS Aero 9 similar amounts over the last 6 years.
It adds a lot of interest, keeps me in the right power range when I choose to be and sometimes I don't chose to be. The rigs are so similar and everything else remains unchanged, so the simplicity of the RS Aero does not suffer and it all fits nicely in the bags under the cover for storage and transport. With alternating two rigs the sails then last much longer too, especially the RS Aero 9 if (unlike me) you mainly use it in lighter winds. You just have options and most keen RS Aero owners choose to exercise that flexibility with a 2nd rig to achieve more good sailing days at each end of the spectrum.
I understand RS are offering a 25% discount off a 2nd rig with new RS Aeros at the Southampton boat show starting tomorrow....


Fair enough ... and I hope they got their money back on the stand
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Peter Barton View Drop Down
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Posts: 129 		Post Options Post Options   Quote Peter Barton Quote  Post ReplyReply Direct Link To This Post Posted: 11 Sep 20 at 7:53pm
Originally posted by Riv

"Hull has a lower increase in surface area drag for the increase in displacement"

Can someone explain this statement? I thought that as a sphere as the maximum volume for minimum surface area that a rounded hull like the laser would gain surface area at a lower rate than a chined hull.

You are right, a sphere has the minimum surface area relative to volume. 
However we are considering the change in surface area between a 35kg and a 105kg person. The low chine and vertical sides mean that a 35kg sailor is already at max waterline beam and adding weight then gives a lower increase of wetted surface.
At the recent Eastbourne Nationals with over 100 sailors weights ranged from about 44kg-105kg. We have had 35kg sailors enjoying the RS Aero 5 up to about 15kn.
 
From the original RS Aero datasheet;
'The early prototypes had a higher chine, however through development, the chine has dropped to just below the water line amidships. This has proved to have several advantages: 
• A 35kg sailor gains the benefit of approximately the same waterline beam and hence the same hull form stability as a heavier sailor 
• The waterline beam and wetted surface does not change significantly with an increase in helm weight'
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Posts: 4 		Post Options Post Options   Quote andrewwilde Quote  Post ReplyReply Direct Link To This Post Posted: 12 Sep 20 at 1:08am

Interesting thread.

Personal perspective, owning a 9 (most of my racing in that) and having used borrowed 7 rigs a fair bit, and being on the heavier end of the spectrum:

I can be competitive in the 9 rig (speed-wise, my tactics and boat handling aren’t up to being consistent) in winds up to mid-twenties (kts). It’s clearly possible to perform well in winds above that (Matt, Greg, etc) but it requires a level of skill (and practice) I don’t have. In a chop, the taller mast of the 9 doesn’t seem to do many favours, as the boat moves around more and the top part of the sail doesn’t seem to help as much as it does on smoother waters. I’m sure, again, that with practice and fitness you can work it through but it’s a rig that is hard to make it work in the stronger stuff. Given a choice I’d move down to a 7 at around 18kts sustained or gusts of over 22kts, but the 9 is probably better for my technique & improving my skills. The 7 feels bogged down under 12-14kts given my current 102kg (a bit too much lock-down snacking...).

In the lighter stuff & on inland puddles I can be quite quick, but it’s really critical where you put your weight fore-aft; as my weight has changed I’ve seen the difference get a lot more dramatic around 94-95kg – if you’re heavier than this it’s hard getting the boat going in light airs (<5kts) and it slows up quicker than those around you (I’m thinking it’s much harder to keep the tail from digging). Once you’re over 100kg, this becomes pronounced. That said, as soon as you’re out of the drifting conditions and sailing in 4-8kts the boat picks up again and you can make it work providing you keep forwards.



Edited by andrewwilde - 12 Sep 20 at 1:10am
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JimC View Drop Down
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Posts: 6662 		Post Options Post Options   Quote JimC Quote  Post ReplyReply Direct Link To This Post Posted: 12 Sep 20 at 9:07pm
Originally posted by H2

is there a future for the 9?

If you look at the races recorded on the PY table its one of the most popular classes in the country, so I'd say the answer is definite yes. Similarly with such a large body of data the yardstick calculation is going to be a decent reflection of the active fleet as sailed in the clubs.
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