Prop tuning question...

[Athito]

I am running a Sunseeker Superhawk 34 with a pair of 300hp Yanmar LP and Bravo III drives on 26" props.

I have had the props lab finished at Steel Developments (excellent service BTW!) but am still only getting around 3600rpm and not 3800rpm.

This is on a recently power washed hull.

Obviously I am more heavily loaded than when Sunseeker did the original matching of engine, drive, prop but I want to try and get the engines to a place where they are running as close as possible to manufacturer's specification and looking for good performance.

I know going down a pitch but turning at 3800 may cancel eachother out but at least the engines will be turning without undue load.

Anyway...here's the question: with what load should I be doing the testing before getting the pitch changed at Steel Developments?

2 crew
Full fuel 700 litres
Full water 60 litres
Aiming for 3800rpm

Or 2 crew
Half fuel
No water
Aiming for 3800rpm

Or 2 crew
Half fuel
No water
Aiming for 3900rpm to cater for mid-season growth and more fuel and more passengers

Or some other magic combo?

Typically there are just 2 of us on board...

[jw.]

In top speed terms I think you are right in that going from 3600 to 3800ish will almost cancel out but the boat will be better otherwise, acceleration, climbing the hump, low speed manoeuvring etc. so it is worth getting right. I makes sense to do your setting up with what you consider to be a normal load for your boating. IMHO

[Renegade]

I would just speak to dave about that, he'll know what to do.
Just tell him what you are after.
Paul

[motorvator]

Stef might be a silly question but you have checked the no load max rpms etc first?

Be daft to resize props if the engines are not running at their absolute optimum.

[Athito]

Hey Kerry!!

Yep. Fuel pumps serviced, new injectors etc etc...

Last thing is the bits of metal in the water!

Loving the South Coast BTW after our chat at Harwich.

[motorvator]

Left Harwich on the Sunday morning and was on the new toy in Marseille the following morning. Had three weeks on board there and got it trailed to Calais and bought it across.

Spent all my time since getting things up to speed including major services on both Detroits. Funny enough I have totally the wrong props on (2 under dia, 3 under pitch and one blade short but close!) but haven't splashed the £3.5k needed till I can get the last 50 rpm out of the engines. Just one turbo and a clean out of tanks left to do.

Mountains of other work to do on her but the important stuff like cocktail cabinets and icemaker are working!

Might get down the South this year but have noticed that 1100hp and an extra 12' is taking it's toll on the wallet a bit!