Fresh Water versus Salt Water

[Targa Ian]

Does anyone have a formula to convert Standard Times for various boat-classes
to allow for salt water conditions?

Cheers,
Ian

[Rob Plater]

I think you'll find this one particularly hard to find. There are a lot of
variable such as water temp as well as all the impurities in the water (including
salt, heavy metals etc.).

[CaptStash]

It's really not necessary as there is very little difference. The change in
displacement volume between salt water and fresh water for a rowing shell is
negligible. As an example, my 900 ft. oil tanker, when fully loaded,
displaces about 110,000 long tons at a 49 ft. draft, yet it only sinks about
13 inches when going from salt water to fresh water.

Regards,

CaptStash....
"Rob Plater" <r...@dutchie.net> wrote in message
news:3A23421D...@dutchie.net...

[Katy]

What about nasty surfactant that local factories pump out periodically?
It's sometimes like rowing through miniature icebergs of horrible foam
here.

KT

[Douglas MacFarlane]

In article <3A23C259...@cs.strath.ac.uk>, Katy
<kaca...@cs.strath.ac.uk> wrote:

I don't know - youngsters today think they have it hard. I remember when
the whole river was covered in foam and the oars made a very muffled noise
as they entered and left the water. It did encourage neat rowing with
no backsplash and blades well clear on the recovery though. The Clyde
may not be paradise but it is much better than is used to be. The swans
and cormorants on the stretch we row are evidence of this.

Cheers,

Douglas

[Anu Dudhia]

Targa Ian wrote:

> Does anyone have a formula to convert Standard Times for various boat-classes
> to allow for salt water conditions?
>
> Cheers,
> Ian

Never heard of such a thing. If there were any difference I guess it would
depend on a change of viscosity with salinity, but you'd also need to know the
salinity before you could use that information.

[Leo Lazauskas]

In article <20001127132009...@ng-mh1.aol.com>,

targ...@aol.com (Targa Ian) wrote:
> Does anyone have a formula to convert Standard Times for various boat-
classes
> to allow for salt water conditions?
>

This would be difficult to do with any confidence in the accuracy. The
drag is different due to water density and viscosity differences. A
simple, crude way would be to use a program like Michlet to calculate
the total drag of a rowing shell in both salt water and fresh water and
over a range of speeds, and then to scale the times accordingly. A more
sophisticated method would be to scale the times according to changes
in the wave drag and in the viscous drag independently.

Good luck!
Leo.

Sent via Deja.com http://www.deja.com/
Before you buy.

[Mike De.Petris]

In uno strano messaggio del 28 Nov 00 capts...@home.com (2:333/608.1)
scrisse al povero All :
c> It's really not necessary as there is very little difference. The change
c> in displacement volume between salt water and fresh water for a rowing
c> shell is negligible. As an example, my 900 ft. oil tanker, when fully
c> loaded, displaces about 110,000 long tons at a 49 ft. draft, yet it only
c> sinks about 13 inches when going from salt water to fresh water.

I disagree with this, I train on the sea always, and I really feel the
difference when going on rivers/lakes, the boat sinks more and you may need a
different rigging, and it is even worst with leverage ! Not only the boat
dives more and find different drag, but what you will feel is the different
slippage/resistence of blades in the water. I can't help building a
conversion formula, but I think the difference is around 10" for a 2k race,
slower with salt.

Ciao, ** *Mike* ** www.interware.it/users/mike/ mi...@interware.it

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[CaptStash]

I think you are kidding yourself. I ran the numbers, and the change in draft
for a single going to fresh water from salt water is roughly 2 mm (less than
0.1"). Specific gravity of fresh water is defined as 1.00, sg of salt water
is nominally 1.025. As the change of draft is small, there is no change in
hull length or beam due to change in draft. You will have a greater change
in draft the narrower and shorter your boat is. I used a length of 792.5 cm
and an average beam of 15.25 cm. Difference of viscosity is also quite
small. The difference you are feeling might be differences in water
conditions perhaps?

Regards,

CaptStash....
"Mike De.Petris" <mi...@bbsgate.interware.R.E.M.O.V.E.T.O.R.E.P.L.Y.it> wrote
in message news:18647...@bbsgate.interware.R.E.M.O.V.E.T.O.R.E.P.L.Y.it...