3 blade v's 4 blade

[23-sharkcat]

I have a 23' sharkcat with twin mercruiser 470 (4cyl 170hp) with 14.25 x 21p s/s props that are not in great condition. Looking at a set of new props.
here is the dilema..............

Current props get top speed of 41knts/h (72klms/h) at 4200rpm and cruise at 27knts (56klms/h)at 3400rpm. Get fantastic fuel fiqures when cruising of about 1klm per litre of fuel(0.5l per engine per klm) and great get up and go.

If I go to a 4 blade prop do I stay at the same pitch or not. Seeing that i easily reach max revs with the current props would I be better maybe sticking to the current 3 blade and getting say a 23p.

http://i66.photobucket.com/albums/h258/rxv3000/DSC00064.jpg

[Blackened]

G'day
I'm not an expert on props but i'd suggest you call someone who is. Send an email off to solas. Just do a google and i know they're great on customer service.
Dave

[Spaniard_King]

Good idea to contact Solas, if they have some 22's they could be worth a go. You seem to have a good thing now why change???

You could go backwards performance wise loading up the engines with a 23.

Garry

[Jonli]

I have 4 bladed props on my boat , I was told by the Teinbridge staff that 4 bladed props are smoother and better economy in cruise but lower top end speed than 3 bladed props which tend to have more blade areas . As for pitch , I can't remember but there is either a reduction or addition of 2" , one way or another . :-?

However it may not be the same for outboard , I am talking about inboard here . :-[

JonLi . 8-)

[23-sharkcat]

Dont worry I am not complaning about the performance. You would not see to many boats of this size that have a top speed like my cat, not to mention the great fuel consumption figuires.

I dont know if I would be loading the engine up to much but I suppose thats why I am asking the question.

As for solas I talked to them at last years boat show about the set up I had and they told me that there is no way a sharkcat of that size with that engine cofiguration could do that speed and would be expensive to cruise around in.

From the states I can get 2 new S/S 14.25 x 22p 4 blade props with new hub kits for under $1000 delevired. Solas was around the $1700 mark for the same thing.

Does any one else have a 23' sharkat with inboards or outboards and what size props do they run.

I think the difference between the outboard/inboard would be the torque. the 470's have bucket loads to spare.IMHO