Merry Fisher 805 cruising and max speed

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From another MF805 owner (i.e. real life rather than theories):
Nanni 200, WOT = 3,650rpm, 21 knots

All other factors as quoted by OP (but includes rope-cutter).

Edit: no hesitation in getting to WOT, throttle lever moved steadily to max as speed increases, not just pushed wide open.

[/ QUOTE ] Thanks for the reply! I have been wanting to talk to other 805 owners. Not sure what WOT & OP mean though.

My 805 has the keel protector & rope cutter fitted.

Do you have the TDI engine or the common rail T200. Mine has the TDI.

Sounds as though mine is not far of the mark & peforms as you mention. Slow to pick up if you push the throttle down hard.

I had also notice that at full revs (around 3600) she will suddenly drop off down to 3400/3500.

I understand that the boat is not built for speed more for comfort. It certainly fits the bill there. I love the boat but could not reconcile speeds qoted for the boat.

Thanks for your reply. You are the first MF805 owner to get back to me.

Would be nice to keep in touch!
 
Have you taken sea state into account? A slight chop can take off a few knots boatspeed. Our 20' Orkney achieved 26 kts flat out on glassy calm water but small waves 0.3 - 0.5m would knock off 4 - 5 kts.

Incidentally I believe that WOT stands for Wide Open Throttle, i.e. flat out.

OP means Original Poster.
 
[ QUOTE ]
Have you taken sea state into account? A slight chop can take off a few knots boatspeed. Our 20' Orkney achieved 26 kts flat out on glassy calm water but small waves 0.3 - 0.5m would knock off 4 - 5 kts.

Incidentally I believe that WOT stands for Wide Open Throttle, i.e. flat out.

OP means Original Poster.

[/ QUOTE ] Thanks for your reply and the definitions!

You may have a point there!

I do not think that there is much wrong as clean bottom and engine serviced and tested by a Nanni dealer.
 
It seems you got your answer from Ahoy2. Looks like the manufacturer's performance figures are woefully optimistic. Did you test drive any other MF805s before you bought yours? If so, did any achieve more than 20kts?
If the revs are not constant, it's possible that the friction setting on the throttle lever is not set properly and the lever is slipping back. It's quite a common problem
Thinking about it, 200hp is not a lot to push a 27ft boat along especially with shaftdrive so maybe 20kts is all you're going to get
 
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If you shout Nanni...na na de na na.. it might be spured to a mightier speed.

[/ QUOTE ] I give it a try! I shouted at it though but it didn't respond.
 
[ QUOTE ]
It seems you got your answer from Ahoy2. Looks like the manufacturer's performance figures are woefully optimistic. Did you test drive any other MF805s before you bought yours? If so, did any achieve more than 20kts?
If the revs are not constant, it's possible that the friction setting on the throttle lever is not set properly and the lever is slipping back. It's quite a common problem
Thinking about it, 200hp is not a lot to push a 27ft boat along especially with shaftdrive so maybe 20kts is all you're going to get

[/ QUOTE ] Ahoy2 has been a great help! I can share info with him which is helpful as he has the same boat.
Thanks for your input!
 
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
 
[ QUOTE ]
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

[/ QUOTE ]

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
 
Yes. If you want some general shots, check out www.seadee.co.uk I fitted a Webasto last year (loads of brownie points with SWMBO). There's some shots of that on there. If you want any comparison shots, let me know and I can e mail you - I've got most of the photos at home !! Relax and enjoy her - you'll be pleased you bought a MF805.

CD
 
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 ?
 
Nice site mate. Although we've now moved, we had our former boat at Pin Mill last year. So we recognise a few of the places in your pics.

[ QUOTE ]
Yes. If you want some general shots, check out www.seadee.co.uk I fitted a Webasto last year (loads of brownie points with SWMBO). There's some shots of that on there. If you want any comparison shots, let me know and I can e mail you - I've got most of the photos at home !! Relax and enjoy her - you'll be pleased you bought a MF805.

CD

[/ QUOTE ]
 
HI All,

Sorry to re-kindle an old thread, but thought there were already some useful facts in it.

We have recently purchased an 805 (Nanni engine) and couldn't be happier with it, it has been brilliant - lots of use already.

A quick prop question.....

When we bough the boat she achieved the full 3600 rpm and approx 21 knots. She was empty, but does have a rope cutter fitted and the 'prop protector' as described above (if this is an optional extra?) Inevitably she now has some growth (2 months?), well more like slime I guess. We have also started loading her up - dingy, outboard, good selection of warp, full tank of fuel, water etc. We are now down to circa 19 knots, which is fine, but I am concerned that we are not achieving the full 3600.

I suspect it would be beneficial to have the prop 'tweaked' or replaced to better reflect every day use. I wish to change it to reduce strain on the engine and perhaps gain some fuel economy.

I was once told / read that manufacturers put a higher than ideal pitched prop on boats as the figures look good when new, but do not reflect normal use.

Has anyone changed their prop and if so can they advise what to fit?

Thank you for your help.
 
Craig MF805 said:
I suspect it would be beneficial to have the prop 'tweaked' or replaced to better reflect every day use. I wish to change it to reduce strain on the engine and perhaps gain some fuel economy.

I was once told / read that manufacturers put a higher than ideal pitched prop on boats as the figures look good when new, but do not reflect normal use.
Click to expand...

I don't know about that theory, although I agree that around 21 knots is accurate for a lightly loaded MF805 with a Nanni engine and no weed. 3600 rpm at WOT. With rope cutter and prop protector. Flat calm.

May I suggest that "to reduce strain on the engine and perhaps gain some fuel economy" the easiest way is just to throttle back a bit. Running at, or close to, 3600 rpm uses loads of fuel! Also she will run hot and noisy.

Sure, open up now and again to knock some weed off and blow away the cobwebs, but for general use about 1900rpm is relaxed cruising - and a lot cheaper!
 
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A friend of mine has a MF805 and he has volvo penta 200hp which gives him 22knots at WOT so the nanni engine is giving about the same sort of performance.
 
Thank you for your replies. It will be interesting next time she is power washed to see if the speed and revs come back up - will then know if it is is the slime or weight that is costing us. Agreed about relaxing cruising, but for weekend breaks it's good to be able to get there quickly. We don't find the Nanni engine at all noisy and runs surprisingly cool compared to other older marine engines that I have experience of.
 
I thought it may be useful to post the outcome of this - I've recalled that I did not do so a few years ago! I had replaced the primary and secondary filters, but the problem remained. I then thought I out to check the tank pick-up and sure enough the strainer on the end of the pick-up was clogged with black gunge aka the diesel bug. Removed the strainer, replaced the primary filter a few times, treated with Marine 16 for 18 months and not had a problem since (touch wood)! I guess we top out at 21 knots with a rope cutter fitted, but rarely pull the full 3,600 - more like 2,550 occasionally touching 2,600. Hope this helps someone some day! Chuffed as ever with the boat - they really are fantastic big; small boats!
 
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