Propeller size

[LiamS]

I have a steel motor yacht.She weighs just under 14 tonnes and has a draught of about 1.2 metres.She is a displacement hull and 36 feet long.I have twin Ford diesels 2.5 litre (Ford transit) engines.She has three bladed props Iam unsure of the size.At about 1500 revs I am achieving about 5 knots would an increase in propeller size be likely to give me a significant increase in speed as I believe these engines can deliver a lot of power

Many thanks for your advice.

 

[brianrunyard]

I should think you ought to get more like 8 to 9 knots.
There's a couple of links on my website to prop calculation programmes, take a look at PropCalc, for starters.


Brian
http://homepage.ntlworld.com/brunyard

 

[stamfordian]

I not sure but are the motors flat out @1500 revs??,you should produce approx 150hp out of the two together, 1500 seems a touch low?,.I am in the process of fitting one of these engines in my prodject but hav,nt got hold of max power @rpm table yet,will let you know if no answer on here.
regards,
T.b.

http://www.arweb.co.uk/argallery/stamfordian

 

[seajay]

The new 2.5 Ford give high power at about 3000 rpm. but what gearing have you got? Best to have a look at Lanncing Web Site.
http://www.lancingmarine.com
Mike.