Ha ha that's the one!

Prop Shop.

Chris

Yes I experimented with a load of props, x, s two blade, 3 blade, and so on. Using data logging by eagle tree I was able to compare actual results, run time, amp draw, speed and so on. The x 2 blades where very good, I think the best size was 52mm, but that cleaver prop was specially commissioned by Simon, gosh cannot remember the company name! But he makes brass props. At the time he had some props in development and used me to try a few. The design of the blades gives it more push and less cavitation, and it looks nice! I sent him all the data. I can also change the gear ratio as its belt driven to suit the lake I was running on, fast acceleration and lower top speed on a small lake, a d better top speed on a big lake. I love the meddling and testing. A single screw v shape very heavy hull single screw will reach a point that it's reached its maximum speed, I got there with this boat!👍

Do you only use the three bladded props? Your brass prop does look a little aggressive with it's pitch. I found using two bladded props and taking several different size props and swapping until I got the response that I wanted. I took the standard props as well as the ones marked with the s on them as they used to give a better response and speed as they are the sport props. I liked to play about with different props just for the fun of it. I have a bag of assorted different sized ones. This once again is just a suggestion NOT a criticism.

I see you say that the boat want's to roll over. I used t0 get that on my Huntsman and my Spearfish. Someone told me that if I trimmed the rudder front leading edge off up to the down shaft and then round the bottom of the leading edge, that this would stop it from digging on the turns and wanting to roll over. I tried it and it did work. From then on I have done it on every model boat I have built. This is just a tip you could try. I am not criticizing your build at all so I hope that you do NOT take offence to my suggestion. Happy modelling and boating 👍

Hi,

I don't come here very often these days, picking this thread up a bit cold, attached is a pic of my prop, its called a cleaver. I tried many props, I like meddling, better than just sailing. I had an onboard data logger that measured amp draw and gps speed. Propguy helped me a lot and is worth a call if he still trades, I always said I would convert this boat to twin screw but never got round to it. When reaching max speed which was 25mph, the hull gets very unstable, as it want to roll over! Its a veron Huntsman 28, 4 foot long

Yes, thanks Alessandro.

As is often the case there is no right or wrong answer just choices. For sports cruisers a 3 blade prop is ideal as it gives plenty of shove and enough speed for planing boats. As I said 2 blade props are used but as alluded to they tend to be better suited to high speed and racing boats but sometimes they do use 3!

I've never heard or seen anyone using a 4 blade in a Fairey.

Hi Wez, not having experience with fast speedboats I would also have taken ChrisF's opinion into consideration.
I have seen how his opinions and advice are always thoughtful and well-reasoned, but above all based on direct experiences.
Often practice in RC naval modeling is more useful than theory, because in scale models some effects are greater and others diminish, you don't get the responses you expect.

Without prejudice to your choice, just for a chat, I'll tell you that (all other parameters being equal: diameter, pitch, shape of the blades, materials) the more the number of blades increases, the more the speed decreases, but there is more stability (less vibrations), the more the number of blades decreases and the faster but more unstable the propeller.

If you are interested in the propeller, we talked about it in the following topics:

forum/1353777

wiki/137058

Thanks everyone was going to get 3 bladed prop anyway as the Vosper had 4 bladed prop and was a little smaller than the 47 huntsman I know a few have put 4 bladed but was making sure I was choosing the right prop and 3 it is from howes models as need to get the 18 in shaft and coupling as well so I can get that fixed I place to get the bottom re painted

Maybe this picture would be of help?