Princess top speed

[traceyandsteve]

can anyone tell us what the top speed of a princess 470 with 2 x tamd 71 (425 hp) should be ???? also the cruising speed please. We are picking her up this weekend and she is only making 26 knots after having over 5K spent on the engines, would this be right ??.
Full fuel tanks, new clean bum, half water and none of Tracey's personal effects

 

[markc]

I thought the TAMD 71's were either 358hp or 380hp (b) version. If so, then I would guess 28knt would be about the most you could expect....IMHO of course!

Mark

 

[Deleted User YDKXO]

T+S, I had a 470 with 442hp Cats and she did 30 knots flat out with a very easy cruise of 22-24knots. Firstly I dont think the Volvo 71 series engines were ever fitted to the 470 unless you have an oddball. I believe you have Volvo 72A engines which were rated at 430hp each. Because these are lighter than the Cats, I would also expect a 30 knot maximum with a similar cruise. I think you should do the following:
1. Check exactly which engines you have
2. Is the speed you are quoting from the log? If so check it is correct with a GPS and do speed runs in both directions to cancel wind/tide effects
3. Check engines are achieving max rated RPM under load which is stated in the manual (probably 2600 or 2800 rpm). If not then you may have a prop or engine related problem given that the hull is clean
4. Ensure that trim tabs are fully retracted for speed runs as having them down could reduce speed

BTW what did the £5k engine work cover?

Keep us posted

 

[traceyandsteve]

I think you're probably right, they may well be 72's. Steve posted this last night without any of the boat info in front of him.

We thought they were 425hp but they could be 430.

We haven't seen the final report from the mechanical engineer yet, but the work covered both turbo intercoolers and various other bits and pieces.

I would certainly have expected it to do more than 26 knots, but maybe I'm just a speed freak )

Tracey

 

[Deleted User YDKXO]

I wouldnt be happy with 26 knots assuming thats the real speed unless you've got some considerable additional weight like a huge tender or a vast generator.
For £5k, I would expect the engineer to accompany you on a seatrial not least for him to check that his work is satisfactory at speed. You can check the max rpm under load as I've said and you can even ask the engineer to check that the rev counters are reading correctly because sometimes they are way out. But also use a gps for the speed runs
Dont forget also that if you're not achieving the proper speed, its possible you might also be using more fuel at any given speed so this is worth checking out
Where's the boat BTW

 

[traceyandsteve]

Have now seen the surveyor's report from the sea trial. Speeds were calculated on GPS, with 20% fuel, small amount of water.

The boat does have a large genny, but no tender at the moment (although we're going to put our 3m rib on it!).

We're not happy with 26 knots, but the surveyor doesn't think it's too far off the mark.

The boat's in Southampton at the moment, and we're taking our old 385 down there this weekend, and bringing the new one back to Burnham.

We'll investigate further when we get down there - always difficult to do these things from a distance.

Thanks for all your input.

Tracey

 

[Guest]

Just looking at the advert for youre boat as they put it "30 knots of absolute luxury" now if she is only making 26 then surely you may have some comeback over this, the other thing is how can they have really spent 5k on repairs, I can sell a secondhand engine for that much with gearbox in perfect working order...
Paul js.

 

[Deleted User YDKXO]

By chance I came across an old 1993 Princess brochure the other day giving tech data on the 470. Firstly, I was wrong to say that only 72 series engined boats were built. According to the brochure, the 71B (380hp) was also offered but I've never heard of a 470 with these engines.
Anyway, I was v surprised by the max speeds quoted in the brochure which were
Volvo 71B....31-33 knots
Volvo 72A....32-34 knots
Now, manufacturers always measure speeds with part filled tanks, a clean hull and, obviously, no gear on board so, in reality, most owners would not get within 1-2 knots of these figures and, furthermore, boats tend to lose speed over time as the engines wear and lose power
However, a max speed of 26 knots even with the 71B engines and, especially, the 72A engines is just too low, IMHO, so keep looking for reasons. Its not just speed you may be losing but also fuel if the engines are not running efficiently

 

[traceyandsteve]

Thanks for all your help guys. Having brought her back over the weekend, we can report that she definitely has 72's which are 430 hp each.

She did only manage 26 knots flat out, but that was with 4 adults on board, plus more stuff than I ever dreamed we had accumulated on the 385 (it took us a whole day to transfer all of it from one boat to the other!).

We also think that there's a problem with the way that the throttles are fixed, as it seems as though she's got more go in her, but the throttles both upstairs and down, just don't go forward far enough. In both situations, they hit the dashboard.

Steve had a bit of a play with the cables on Sunday and has gained a bit of give on the starboard side, so he's going to investigate further. Unless it's a completely daft idea, it looks as though with the cables adjusted, the levers might go further forwards and give us a bit more revs.

We'll report more when we know!

Cheers

Tracey

 

[Deleted User YDKXO]

I had terrible problems with the control cables on my 470. When I bought the boat, the control levers were incredibly stiff - you needed 2 hands to move from neutral to in-gear. To cut a long story short I eventually replaced all of them with special low friction cables at huge cost. I was told by Princess themselves that the cable route has some very tight bends, particularly from the flybridge, and that causes the stiffness
It could be that the cables on your boat have stretched a bit and it could be that the throttle on the fuel pump is not opening fully. Certainly worth checking out