Prop selection

Rupert Bear · 27 January 2004, 16:17

I am curious about SS props. I have a 13x15 alloy three blader fitted at the moment which is spot on but wondering just what difference, if any, a SS prop might make.
I get 29knts@5500rpm with one to two folk on board fully fueled and 22knts@5000rpm fully loaded with 8 dive cylinders, 4 folk and 4 sets of dive kit on board fully fueled. Boat is just over 550kgs before folk get onboard.
Would I expect any appreciable difference if I fitted a 3 or 4 bladed SS prop and if so roughly how much and would pitch need to change?
I am not too bothered about flat out speed when empty, more interested in fully loaded speed, another knt or two would be nice

pmorgan · 27 January 2004, 17:25

It will defiantly make a dent in your wallet – I was quoted £400 replacement cost for mine !
I ended up paying £75 to get the dings ‘buffed’ out !

peteb · 27 January 2004, 18:06

Go here :-

http://www.steeldevelopments.co.uk/Steel_Developx.html

Best around IMHO, great advice given on the phone, very friendly, and very well priced.

thorper · 28 January 2004, 12:36

I agree, steel dev have given some good advice in the past, although we tried one of their props without any noticeable increase in performance.

What you might also want to ask them about is doel-fins, which attach to the bottom of your engine and give extra lift. For a heavily loaded small boat it will help you get on the plane quicker and will support the back of the boat more (they effectively act like a wing at the back of the boat giving stern lift). Fins cost under 50 quid I think and might help you out some. There are extensive threads on this if you search the forum.

Ricky

Rupert Bear · 28 January 2004, 14:52

I can't really use a fin, the boat is too light in most circumstances at the stern anyway (I have a 70l tank fitted up frontas well as the battery and anchor locker). Now if I could get one for the bow...................

Steel Dev · 30 January 2004, 18:44

Generally a s/s prop should make the boat go faster as the blade section on a stainless steel prop is different to the aluminium one. However propellers are not an exact science, as there are so many variables, you can not guarantee a gain but in most cases it is possible.

3 blade vs. 4 blade. The 3 blade prop will have a faster top end speed than the 4 blade. The 4 blade prop will have better acceleration and mid range. Price s/s 3 blade £210.00 + VAT 4 blade s/s £299.00+VAT. As to pitch choice it depends on the make of propeller you go for and the number of blades.

Keeping the prop in tip top condition will make a big difference to performance. Any damage however minimal will reduce speed. Repairs are very cost effective £33.50 + VAT for aluminium or £55.50 + VAT for s/s

Don't forget we are going to be doing the test program at RibEx, I will post a note on the Forum nearer the date of all the details.

If you want to give us a call re prop queries we will certainly be happy to help you the number 020 8874 7059. I don't get a chance to come onto the forum everyday so do not hesitate to give us a call if you need any help or advice