AD31b sluggish running

Corky

Corky

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Hi,

my Hardy Seawings used to run at a comfortable 20-22 knots at about 3000 revs now it won't rev over that level and I'm lucky to get 12 knots out of her. She was haued out and cleaned off only 2 months ago for some seals on the out drive. She has twin VP AD31b's . Any suggestions?

Anyone any idea where I can get a proper wiring diagram for this boat?

Thanks
 
Just sounds like the bottoms dirty mine has lost all its go in 6 weeks from her scrub off.

The 31 doesnt have much torque thats why shes so slow, has alot of lag below 3000 rpm.
 
I've got AD31P's the 150hp versions in a very similar 32ft boat, everything has to be spot on for it perform, clean bottom, no dings in the props, new fuel and air filters. As Volvopaul says they have no torque below 3000rpm which is the minimum to get youi planing so any small thing will knock you back and reduce performance. Try new fuel filters and check the props if your sure the bottom is clean.
 
Thanks for your thoughts. They are brand new props (well 2 months old) fitted when she was last hauled out and the hull cleaned so it's unlikely to be props or hull. I'd been wondering if it might have been air filters but with it being both engines it seems a bit of a coincidence. Wasn't aware that there was little torque below 3000 revs, is there a modification you're aware of to change the torgue curve? Preferable reasonably priced (if there is such a thing for a boat).

Appreciate the input.
 
Acutaly I should have said not much torque anywhere, if you look at any boat model that was fitted with AD31's most were subsequently upgraded to AD41's or KAD32's, i'm afraid there is no sustitute for grunt.
 
AD31B sluggish running

D'oh - typical !

The only other thing I thought of, considering the comments around needing everything spot on, - is that I'd filled the fuel and water tanks before the journey. I realise that could be a lot of weight to carry.

Cheers !
 
Corky said:
D'oh - typical !

The only other thing I thought of, considering the comments around needing everything spot on, - is that I'd filled the fuel and water tanks before the journey. I realise that could be a lot of weight to carry.

Cheers !
Click to expand...

Full tanks won't help if you have another problem but it should still go, I'd change the fuel filters first before doing anything else.
 
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