Underpowered?

Leman805 said:
Yes it does feel sharp until I'd say around 2'000 rpm (not sure about the exact value) with instant response to throttle movement. After that it feels as if the hull was loaded with water and the engine was painfully keeping it on plane. Acceleration from minimum planing speed to maximum speed is really slow.
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Whereabouts are you moored?
 
PhillB said:
Hi all,

I looking at a 8.25Mtr Sports cruiser from the US side of the pond. My only reservation is that she is powered by a D4-210 which I fear is underpowered for a 3,500kg 8.25Mtr boat.

I know modern diesels have come on a long way, but what are your thoughts - I would be much happier with 260plus, but am I wrong?

I dread investing in a boat that struggles to get on/stay on the plane.
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Is that the Larson on the Thames somewhere?

The D4 210/220 hp doesn’t have the supercharger of the 260hp D4 or KAD engines so is a lot more sluggish to plane - should run ok when up and going tho - not sure that boat is 3500kg if it is that one - more like 2500-2700kg

I discounted it for same reason, is a decent river boat but others on here said not a good sea hull but I’ve no experience of it - sea trial only way to tell.

805 is better boat but £35-50k I think - next price range up really
 
I did a little looking and your V8 Petrols book around 100kg lighter than the D4 Diesels.
However, Max RPM I've seen is quoted by Volvo at around 5000rpm so you appear to be running down on max rpm at WOT.
Also the torque curve of the V8 petrols - from experience (I ran a V8 petrol for a while) and talking recently to a guy who has just repowered a twin V8 petrol boat for a pair of VP diesels, the petrols do feel like they are working hard to get up on the plane. I did a little research and It appears the 5.7GXi has around 150nm less torque than the VP D4 260 diesel and will likely be delivered higher up the rev range than the D4.

All that would suggest a boat that takes some work to get up on the plane and doesn't have a huge planing window. I'd certainly check your WOT rpm as if you're only getting 4400 that is around 600 below VP's own specs.

Just my thoughts I hasten to add.
 
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