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In article ,
(Matteo) wrote:

i post this update after changes to the trimming of the boat.

I said the boat is poorly trimmed and seem to "sit" too much with the
stern in the water.

So i put around 3/4 of tons of water (750 liters) in the anchor room
(the small cabin in the bow which contains the chain - is quite large
and sealed).

This had the effect to sink the bow around 8 inches and lift the
stern around 3 inches. The boat is still NOT level but at least is
getting closer.

Now the effect on travelling speed:

I could reach 5.5 knots at 900 rpm instead of 1100 rpm ! And my fuel
consumption went down 40% at once (for the same speed).

That's a significant difference! Sounds like you need to make some light
stuff in the bow area trade places with heavy stuff in the stern, even
if I interpreted correctly that you can add fuel forward. There are
other things I can say, but I don't even know if you're cruising or
day-tripping.

Something else to look at is the prop. Friends of ours have had their
Marine Trader for many years and maxxed out at the same speed all those
years. In preparation for their first Bahamas trip, they re-propped.
They gained a couple of knots of top end, cruise at a lower RPM and
better economy, but higher speed than they used to. Nothing else was
changed.

At a minimum, send the blade off for a balancing when you get a chance,
as a simple mis-alignment of blades can make a big difference. We did
that for a two blade prop with only 100 hours on it and got a noticable
improvement. The two blades were pitched a full inch differently. Who
knows what an old, heavily used prop looks like?

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

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