KAD32 WOT/Props

[Mexican]

Currently on newish boat to me am only getting 3500rpm WOT and wanted advice from the 'panel' as to which props top move to so I can achieve recommended 3700-3900rpm. Am assuming it may be down to wrong props, engines will freely rev to 4000rpm in neutral regularly serviced etc etc Have recently fitted new tachos checked for accuracy with IR meter. Current props are A5 - am I on the right track?

 

[petem]

What boat is it?

 

[Mexican]

Bayliner 3055

 

[Momac]

Potentially expensive messing with props.
What speed are you achieving at 3500 rpm?

 

[Mexican]

With clean bottom around 27/28 knots

 

[steve930]

I've got a 30ft larson with twin kad 32's. I'm running a4 props and achieve maximum revs, which is just over 29 knots.

The figures tally with the volvo prop guide

 

[Mexican]

What sort of weight is your Larson, think my boat is around 5 tonnes as hoping in excess of 30knots WOT - similar to Sealine S34 (similar size/weight?) . Does anyone know if the A4 prop pitch is less than A5 as can't find this info, also understand that A series props replaced by J series - anyone with experience in changing to these?

 

[Ian MacAulay]

I have changed to J8 props and was on A7 props... I had loads of issues with under reving and so on so I changed fuel pumps props and gave engines a right going over to find it was my trim tabs stuck causing drag! I spoke to Volvo who done all the calculations once I got the tabs and so on all sorted.

Ian

 

[steve930]

Mine weighs about 4 tonnes. The a4 is a lower pitch, so more revs/less top speed.

With boat fully loaded with fuel, water etc I'm still seeing maximum revs this far into the season. I did consider going up a size but by doing that I may risk getting on the plane easily ( as she does now) so I think I'm gonna leave her as is!