"Wayne.B" wrote in message
...
On Sun, 4 Nov 2007 10:19:34 -0000, "JimB" wrote:

Of course. Sorry, speaking as a sail person. But you'd have a good idea
what
your suitable astern revs were to check proper holding?

I ususally start with one engine at idle speed which generates about
600 lbs of thrust, then reverse the second engine for a total of
around 1,200 lbs. That will take the catenary out of 3/8ths chain and
begin to stretch a 7/8ths 3 strand nylon hook line. If I want to
really ensure a good set I'll bring the engines up to 900 RPM or so
which begins to really stretch out the hook line. I'd estimate well
over 2,000 lbs of pull at that point with the engines putting out
around 40 hp each into 30 inch 4 bladed props.

Great. Should look after a good F7 as long as there's not too much seaway.
It always amazes me how so many people don't test their set, then wonder why
they drag.

Another bit of useful info you get from testing is how much rode you need
for your anchor. Some stick beautifully at 4:1, others need 6:1 minimum.
--
JimB
Google 'jimb sail' or go www.jimbaerselman.f2s.com
Compares Cruise areas of Europe