Merry Fisher 805 cruising and max speed

My MF 805 did just over 22 knots this afternoon. Recently antifouled. no prop guard, water tank empty. 2/3 full of diesel, no tide and no passengers.
 
molyneux said:
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Hi - another MF805 owner with the real view on life. Forget 20 knots plus, mine's never done that. Exactly the same spec as you. Mine sits at 3,000 revs all day long and I'll be somewhere between 15 and 18 knots without and with the tide respectively. Occassionally I open mine up "bongo styleee" but for the extra couple of knots you get a huge increase in fuel consumption and a truck load of noise. I tend to agree with you - these boats are about solid crusing, not going fast. My old MF625 with 90hp Suzuki was 30 knots easy but in a big sea you needed tight pants. The MF805 looks after you good and proper. Jeanneau will tell you all sorts of rubbish to get you to buy the boat. Chill back, stick the kettle on and you'll get to the next port eventually.

CD

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I much appreiciate your response as it gives me a measure. I am pretty sure then that there can't be too much wrong with my boat then.

There is always a danger in comparisons. I previously had an Avon Adventure 560 RIB with an Yamaha 80hp 4 stroke. We could get 40mph recorded on the Garmin GPS flat out.

The MF805 after that seems to stand still although I much prefer the MF805 for the reasons you mention! The hight above the water on the plane at the wheel appears that the boat moves slowly. When you look to the stern you realise is isn't.

Just out of interest, does yours have the 3 way valve and holding tank?

Thanks for replying to the thread!

It's really nice to hear the views of other MF805 owners.

regards

Paul
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Hi, My 805 has the 3 way valve. I've never fully understood how it worked. Any tips?
Eamonn
 
My 805, with 2 people on board, various equipment , 3/4 of fuel an full water, has reached 21.5 knots, with the Volvo Tamd41p and a perfectly clean hull. The engine was over revving at 4000-4100 rpm.
After two weeks, it was able only to reach 18-19 knots. The reason was the hull, already dirty again...
Another consideration is that the Volvo is 150 kg heavier than the Nanni: it's like having two more people onboard, but I think it's a bit more powerful in the real world, than the Nanni.
 
Vale72 said:
My 805, with 2 people on board, various equipment , 3/4 of fuel an full water, has reached 21.5 knots, with the Volvo Tamd41p and a perfectly clean hull. The engine was over revving at 4000-4100 rpm.
After two weeks, it was able only to reach 18-19 knots. The reason was the hull, already dirty again...
Another consideration is that the Volvo is 150 kg heavier than the Nanni: it's like having two more people onboard, but I think it's a bit more powerful in the real world, than the Nanni.
Click to expand...

5 year old thread.. :)
 
PaulGooch said:
I have a 2003 MF805 with the Nanni engine. Don't carry masses of weight, fitted with rope cutter and prop protector from new. With 4 on board she'll reach 300RPM very quickly and easily get to 3600RPM. Nailing the throttle she'll smoothly pull up to max speed. Depending on the tidal flow, she'll do between 22 and 23.5 knots, as shown by the GPS. At 3000RPM, which i find a nice cruising RPM, she'll do 16 to 19 knots, depending in tide again.

Your RPM should hold fairly steady, something doesn't sound right there. The "keel protector" you mention sounds more like a prop protector, 3 or 4mm thick piece of channel ?
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I agree, if not fuel then maybe the engine governor or ECU? Not sure why else the issue is in the 3200 to 3500 rev range and not at full bore if fuel restriction is the problem.
 
In the last 15 years i've had a 635, 655 and 805, all semi displacement and they all did about the same, 20kts with a clean hull. By October with a bit of weed on the bottom it will do about 16kts if you lucky
 
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