Nimbus 280 Fuel Efficiency?

[Kawasaki]

Thanks Kawasaki

I'd seen your earlier posts, knew you had a similar boat (until today)

The prop dimensions etc would be great info. I have no manual to go by, only what I can glean from online sources - and those are thin on the ground for this boat.

Just to check this ....

Does this mean that you go to cruising speed with tabs all the way down, keeping the nose down, and then you raise the nose by raising tabs a notch?

Yes
I believe with a full planing hull or semi
Leave trim tabs or trimming an outboard or outdrive
There is no point in trimming before you are at your optimum cruising speed
If you trim before that situation you will not let the vessel achieve it's best attitude.
When She is settled, you can then adjust
Trying to adjust during the 'climb' will unsettle the hull and your skull

 

[Kawasaki]

Thanks Kawasaki

I'd seen your earlier posts, knew you had a similar boat (until today)

The prop dimensions etc would be great info. I have no manual to go by,

OK
At the boat tomorrow to clear stuff out etc
The new owner has the manuals and specs etc
But I will inspect the prop dimensions 'physically' anyway
Over my years of ownership I did experiment slightly, with prop pitch
The results of which are 'logged' but as said details are with the new owner
I remember trying to get more speed
The origional prop died a natural death (after 20 years of swinging in the Oggin!) The previous owner, imho stuck a wrong un on!
It transpired.
That prop did ok, until I parked on an area that kinda re arranged the blade shape.
IE , I ran aground due to mis information from the Admiralty chart I was using at the time and really strange tidal effects
Wasn,t my fault, Honest Guv!
So -- by prop 3, She ran much better
Might take or day or two
I will report back
Couple of things you could try
Call Offshore Power Boats
They may have info ref your boat and prop etc
I do have a contact No. for Nimbus in Sweden technical dept
Again, with all the boats manuals etc etc
I have spoken to them on numerous occasions
They are very helpful
Plus they speak English better than what I do innit, like

 

[Lichfield]

Prop for a Nimbus 27

Hi Kawasaki

I wonder if you did manage to get the vital stats on the 3rd prop you had on your Nimbus Familia

My boat is now out of the water, and I want to research if a prop replacement would be a good idea this winter.

Thanks in advance

 

[boatmike]

Dear all,
Thanks for the advice.

PhilipF, from your passages to Brixham it looks as though you’re getting very similar consumption figures to my own (Poole – Brixham 70ish nautical miles / 145 l = 2l per mile).

Kawasaki/Whitelighter, I’ll try increasing the revs to 3200/3400 & see if it makes a difference.

Does anyone know of an after market fuel economy meter that can be fitted?

Familiar question! I have just moved from sail to power and have an Aqua-star 33 with twin Volvo TAMD41A in. While its bigger and twin engines the problem is similar. Neither of our boats are true planing hulls and are best described as semi-displacement. What others have said is only true of full planing hulls. With boats like ours it is unlikely that you will get a big improvement on your figures by going faster, but I do agree with others that at your length 12 knots is over displacement speed. Drop down to 6-8 knots and things will improve dramatically. To give you some comparison my boat APPEARS to consume the golden liquid at these rates (caution it's only based on my delivery trip from Ipswich to Solent so far)
Flat out I get about 18 knots and consume about 4.5litres per Nm. 12 knots it's about 3-3.5. 8 knots its about 2- 2.5. So yours, with a single engine and a smaller boat will have a similar curve I would think but of course consume less at all speeds than I do.

As far as fuel flowmeters are concerned I will be fitting Floscan. It's gonna cost me nearly 2 grand but with only one engine you can get buy with less than half that. Talk to Sam at Merlin

Merlin Equipment Limited, Units 3 & 4, Cabot Business Village, Holyrood Close, Poole, Dorset BH17 7BA.
T: 01202 697979
F: 01202 691919
W: www.merlinequipment.com

There are lots of options but frankly it's the only reasonable bit of kit. Don't be destracted by Petrol options that only need one flowmeter. With a Diesel you need 2. One on the delivery and one on tank return.

Good luck!
Mike

 

[Kawasaki]

Hi Kawasaki

I wonder if you did manage to get the vital stats on the 3rd prop you had on your Nimbus Familia

My boat is now out of the water, and I want to research if a prop replacement would be a good idea this winter.

Thanks in advance

Lichfield
Sorry I missed your request/reply
I,ve had a few weeks without the internet!!!!
Boat now sold
However, the info is with the new owner, I had records/history etc logged aboard
I did check the dimensions of the current prop a few weeks ago
However, as yer do, had a few sleeps and beers since then!
I will contact the new owner and ask Him to check etc
If the thread dissapears I will send you a PM

 

[Lichfield]

Prop dimensions for Nimbus Familia 27

Hi Kawasaki

I know its a while now since you owned your Nimbus, but I wonder if you ever did get the prop. dimensions/spec. I am sure my prop is not original and want to check on a replacement to see if I can ever reach that elusive 16knots or more

 

[Jim@sea]

What we need is a diesel "flow meter". A few years ago I wanted to know how much diesel my boat was using. I thought that if I could find a Flow Meter and it read how much diesel was going through the meter, I could time it at different speeds and work out how much diesel I was using at different revs.
But as far as I know, nobody makes them. Yet.

 

[vas]

will agree with previous posters and will give an example on mine
43ft f/b 2x330hp IVECOs
8knots over almost 200nm consumption constant 1.5lt/nm
So you're definitely doing something wrong, drop speed, or if possible increase speed but dont stick to this 10kn!

V.

 

[PhilipF]

Hi Kawasaki

I know its a while now since you owned your Nimbus, but I wonder if you ever did get the prop. dimensions/spec. I am sure my prop is not original and want to check on a replacement to see if I can ever reach that elusive 16knots or more

Just to add a little: We have a Nimbus 280 aft cabin (termed 'Familia') This was build number 23 out of a "run" of 25 built in 2005. Seems that ours was the only one of that build to be brought into this country.
Nimbus literature claimed that these boats would run at about 18 knots, and I understand from talking to other Nimbus Club Members that their "280's" will go at much greater speeds than does ours.
Last summer I had the boat out of water and had her copper coated. Directly after I took her out to the measured mile off St Aldhems head near Swanage. Running our D3 160 at my usual cruising speed of 3,000 revs. I took times as we passed the posts, making sure of course they were in line as I started my timer. Two runs were done in opposite directions. One was completed in exactly five minutes, and the reverse run timed in at exactly seven minutes; So, a clear result; three thousand rev engine speed, but only ten knots per hour. This confirmed what I'd always thought - this boat is pretty slow!
Now why are these boats slower than Nimbus claim? Several reasons I submit, first being that the aft cabin does add quite a bit of extra weight, and that this was never allowed for by the builders, also of course, like many users we carry a deal of "clobber" that itself adds to weight (we use the rear cabin for sleeping, and the front cabin we do fill with a lot of gear)
All in all, we are well pleased with our aft cabin Nimbus. Great shame that more of this design are not built, though I reckon it would be better if they were based on a "320" hull rather than a "280". Saying that though our boat with an over all length of 8.8 metres suits us perfectly.

 

[Momac]

Just to add a little: We have a Nimbus 280 aft cabin (termed 'Familia')
Nimbus literature claimed that these boats would run at about 18 knots, and I understand from talking to other Nimbus Club Members that their "280's" will go at much greater speeds than does ours.
three thousand rev engine speed, but only ten knots. This confirmed what I'd always thought - this boat is pretty slow!
Now why are these boats slower than Nimbus claim? QUOTE]

Doesn't the D3 rev to a maximum of 4000rpm?
What's the speed at say 3500rpm?

 

[gjgm]

Just acquired a Nimbus 280 coupe with the Volvo TAMD 31p (150hp) motor. The economy so far has been disappointing. At a cruising speed of 10 knots (2900 rpm) the consumption is approximately 2 litres per nautical mile (2.25mpg) – this consumption has been constant for over 200 nautical miles. The condition of the boat is excellent; the engine has run for 270 hours & has been recently serviced, the hull is freshly antifouled & very clean.

Can any kind forum member shed some light on what the “expected” speed/economy values should be for a 280 coupe?

This is very interesting. Last summer in Brittany we were talking to someone with a larger single engined Nimbus, and he seemed midly miffed to hear our fuel consumption figures, as they were lower than his.
Different boat etc, but the Khamsin is just under 35ft, and we cruise 25-30knots, I guess, with a top speed of 43 knots. Fuel consumption over good distances (like 500 miles cruising- not 2knots in a river but out at sea,) gives a consumption of 2.25-2.4 litres per mile.

 

[PhilipF]

Doesn't the D3 rev to a maximum of 4000rpm?
What's the speed at say 3500rpm?

If you read through this whole thread, you will see that I previously answered this.
On trim tabs, I've long since given up 'playing with them' i.e. they make no difference to either speed or fuel consumption