I was wondering what the effect of weight loss would be on the relative power of my sails.

I'm currently 81 kg and want to reduce to 75. Any weight loss would have the effect of increasing sail area to weight ratio. I theorise that this would therefore increase the relative power of sails roughly equal to an increase in sail size.

Using this process (mathematicians check my logic):

Step 1 - predicted or ideal body weight kg / current sail size m2 = x (your desired sail area to weight ratio)

Step 2 - current body weight kg / x = new notional sail size

...gave me me:

@81kg to @75kg
---------------------------
7.5m becomes like 8.1m
6.5m becomes like 7.0m
5.8m becomes like 6.2m
5.2m becomes like 5.6m
4.5m becomes like 4.9m


The question is is the advantage gained from reducing weight equivalent to that gained from an actual increase in sail size?


The effect would be the same on boards but this is easier to work out. Each kilo you loose has roughly the same effect as increasing volume by 1 litre.

Lose six kilos:

115 becomes like 121
96 becomes like 102
86 becomes like 92


Is this the cheapest upgrade of all?


Note: I understand sailors in WA well might be amused at this. In SEQ every little bit helps.

I think I've put on a kilo or so & it was great! I could hold my 6.6m in 19kts yesterday.

I've probably lost about 10 kgs over the last few years. I do feel a lot more comfy on the water. Actually I hav'nt changed any of my kit accordingly, in fact I mostly use bigger race sails now .......... and I seem to be sailing slower now, although its hard to compare apples with apples. Mabe I should gain weight again just going to grab a beer

Haggar said...

I've probably lost about 10 kgs over the last few years. I do feel a lot more comfy on the water. Actually I hav'nt changed any of my kit accordingly, in fact I mostly use bigger race sails now .......... and I seem to be sailing slower now, although its hard to compare apples with apples. Mabe I should gain weight again just going to grab a beer

Drink beer sail fast

Nebbian,

How does 10kg difference affect top speed?
For example, say in 20kts and you use a smaller sail , would you get the same top speed as 10kg heavier and more sail?

Makes even more apparent difference to your board I reckon. A few years ago I dropped from 100+ to about 82kg and it made my 103L board feel so big I could uphaul my 4.7 with no rope!

JayBee said...

Dropped 33kgs in less then a year. I still prefer my 12 and 10.7m sails.



JB

That's an amazing effort!

If you want some weight loss tips then just ask, it's easy when you know how

Yes pleeeeezzzeee

@Nebs @ ikw777 - Thanks

When I was 119kgs someone described me as "having lots of power". It was a nice way of saying I had righting moment that could be advantageous in some circumstances. Now at 86kgs I get overpowered faster, but changes in fitness have negated most of that effect.

I would have to agree with Trousers, losing mass results in loss of righting moment too and that may not be beneficial. It entirely depends on the discipline you want to do. In waves, being heavy (having righting moment) is not good. For speed sailing it is very much advantageous. In formula sailing AA is not light and is a multiple World Champ, but many of the top sailors are around the 80-85kg mark. Here is Aust, Steven Floyd is one of the lighter sailors around, yet won the NSW Series last year. He uses his 10m sail when most people are still mot maxxed out on 11's.

Trousers also makes a great point - there is a difference between being "light" and being "fit". It is possible to be one or the other, both or neither.
Dieting makes you "light". That means looking at every single thing you eat and evaluating whether you need the calories. If you work at a desk (as I do) you do NOT need to carb load with pasta's, rice or bread. If you feel tired, food will not perk you up.
Exercise makes you fit. Cardiovascular/respiratory endurance, stamina, strength, flexibility, power, speed, agility, balance, coordination, and accuracy.
There is some cross contamination between these. Diet can effect fitness, and vice versa, but it is very much a second order effect.

In general - the only place where weight is advantageous is in a steamroller.

JB

Not to mention the benefits for your knees and hips (one for the over 40s amongst us).

Another way of thinking about it is, if you are currently happy with you power to weight ratio, when time comes to replace sails you can go down a size.

Swap from 7.5 to 7.0 and enjoy a lighter rig on shorter mast and boom. Cheaper and easier to handle but you won't loose any performance over what you already enjoy.

Efficiencies gained all round.