Urgent prop help needed.... Cant find the help i need

Ian MacAulay said:
Loaded at the weekend for these figures i got was 4 people up.. full fuel and water tanks and probably 200kg of luggage bedding and drink/food


Ian
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Well you were probably too heavy to make a call on prop size. Dont make a snap judgement. Go and trial some more under more normal conditions.
 
BruceK said:
Well you were probably too heavy to make a call on prop size. Dont make a snap judgement. Go and trial some more under more normal conditions.
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I tested at this weight as thats probably about right for how it would be normally loaded. Thats bedding clothing fenders and so on and as for fuel and water i like to keep topped up. TBH she was prob -100l of fuel in the tank and 200kg is probably a bit over the top for 4 peoples bedding and luggage.

I'm normally likely to have a couple more people on board most of the time in the summer

thanks


Ian
 
BruceK said:
Forget speed. Look at what your revs are telling you
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Now i have been given the key info that 1 drop in size = 200rpm thats a great help. No one seamed to be able to give me this info before. As I'm sitting at 3500 on a7 props its getting a clearer finally ;-)

To your info does water separators contain filters?

Thanks

Ian
 
Ian,

Stainless props differ one number down from alloy props for the same pitch if I remember correctly. So C4 would be B5. According to volvo stainless is recommended from KAD44 and up as the alloy ones cannot handle all the torque.
Stainless is nice as they don't corrode but I am not sure they match an AD41 setup.

Rob
 
Thanks Rob


Before i take the plunge there is one think i think i demo need to check.... The fuel water separator filters... I've changed everything but these. Unfortunately i don't know what ones to order now to take with me when i next go to the boat.

Ian
 
This might help, although you need to interpret the data correctly - putting a set of A10's onto my boat won't enable it to reach 47 kts!
Yours is probably the AD41P with the 1.95:1 drive ratio.

If it were my money, I would drop one size, and go with a set of A6's, although I still don't understand the rpm/speed figures you were getting. An accurate "through the water" speed indicator, or testing with zero tide and a GPS would help.

props.png
 
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Thanks thats a great chart.

Im going to go saturday and rip out this water separator filters and test in a few directions to get some average figures.

As I've not checked those filters they could be robbing some valuable rpm's and tweaking of the trim may help too

Thanks

Ian
 
One for Volvo Paul, but as far as I know Diesels are the complete opposite to petrol engines in that regard, the leaner you run it the cooler it becomes until the ability to ignite under compression fades. However, running leaner will result in less power available and could therefore be the reason you are not making power and revs.
 
Strange and giving me a head ache... The pact both are doing it too..... Could stale fuel be a issue with timing ?? My knowledge with diesels is limited

Volvo Paul are you about to help?

Ian
 
She pulls very well up to 3500rpm then just stops pulling with no more go... No smoke or nothing strange happening

Perhaps the previous owner was right with saying she was reving high but since then a couple of months have gone by and perhaps seperator filter got clogged

Ian
 
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