Sizing a prop - how?

[peter2407]

Long story short - last year had to have a new prop installed as the Gori folder was causing problems. Decided, under advice, to change to a fixed prop. The prop feels under powered. This is on a sail drive (SD20) with a Yanmar engine (3GM30) on a 36 ft boat of 7 ish tonnes. What size and spec prop?

 

[jakeroyd]

This might help:-
http://www.rbbi.com/folders/prop/propcalc.htm

This is for folders but there are other calulators out there.
Ask Mr Google

 

[Tranona]

Long story short - last year had to have a new prop installed as the Gori folder was causing problems. Decided, under advice, to change to a fixed prop. The prop feels under powered. This is on a sail drive (SD20) with a Yanmar engine (3GM30) on a 36 ft boat of 7 ish tonnes. What size and spec prop?

You can do the calculation yourself using Propcalc on www.castlemarine.co.uk but if you are buying a propeller you should ask the supplier to recommend the size, then if it is wrong you have some comeback. Saildrive props are very predictable if you are using a standard fixed prop and a Yanmar agent will have access to suggested sizes.

 

[vyv_cox]

You can do the calculation yourself using Propcalc on www.castlemarine.co.uk but if you are buying a propeller you should ask the supplier to recommend the size, then if it is wrong you have some comeback. Saildrive props are very predictable if you are using a standard fixed prop and a Yanmar agent will have access to suggested sizes.

Unfortunately Propcalc as hosted by Castle Marine only runs on Windows XP and Vista. I was there a few days ago and can recommend them. If all else fails I suggest you talk to them and feel certain they will advise by phone.

 

[ianj99]

Long story short - last year had to have a new prop installed as the Gori folder was causing problems. Decided, under advice, to change to a fixed prop. The prop feels under powered. This is on a sail drive (SD20) with a Yanmar engine (3GM30) on a 36 ft boat of 7 ish tonnes. What size and spec prop?

There is another calculator here: http://www.vicprop.com