I believe most posters in here knows my project about building a 56 x 12" Cigarette type Mono in plywood.
I see a lot of discussions of what props to use, and I don't understand much of it.
A simple and good advice would be fine.
So here is the setup:

- Blata 40 WRX: mhzusa.com/MHZ-Blata-40-WRX-Marine-m-1531.htm
- Z Twin Drive Speedmaster S6: mhzusa.com/Z-Twin-Drive-Speedm...6-m-1729-T6.htm

The Blata should produce about 13,4 hp at aprox 17.400 rpm and after the loss of power in the gearbox at least 6 hp at 27.300 rpm at each of the two sterndrives.

I will place the sterndrives as deep as possible (as I don't believe in surface-piercing and roostertails).
Each drive is dimensioned to carry a prop up to 72 mm.

The "1000 $ question" is: What props are the best? Quality and effect is everything. Price will not be the question.
I expect to buy from my european retailer, hoping to be able to get the best pair of props from him:
www.mhz-powerboats.com/mhzpowe...ad5b04d7b79cabe

By looking at the site, I imagine (without knowin) that the "Alu Hydro Propeller 70 mm (1470)" could be a good choice. But please look for yourself at this site, and let me know what you think are the best props for a boat like mine.
(I look for answers - not "prop-science").

Merry Christmast to everyone here!Woodie.

Wow this is a good one. I can honestly say I have no idea. Personally my gut feeling would be to stay away from the 26k rpm and try to keep in in a lower range and go with gas props easily accessible on the market, but I very well may be way off with this.

I would suggest running this by the guys on the dutch board xtreme rc boats. They do much more of these twins and different engines etc. Some very knowledgeable guys on there. Tell them I said hi.

Here is a link: www.xtremercboats.com/phpBB/

Hi Marc.

The setup with the Blata, the gearbox and the twin MHZ-sterndrive w. 27.300 rpm output at each drive is actually recommended by the Blata-sellers in US and Europe.
But they don't recommend what propellers to use.
Anyway I'll follow your advice and ask the guys on the other site.
Will register some day after christmas. Seems to be a good forum too.

Meantime any help from the good folks at MGB is wellcome!

Merry Christmas!

Woodie.

I really need to know the simple (basic?) princips about what prop to use on my boat (as described in the above).
Could it be that lots of power and rpm's at a submerged prop (in this case two props) requires a somewhat smaller prop with a very high pitch as this example:

mhzusa.com/MHZ-H50-Modified-Be...ht-m-1263-R.htm

And what is the pro's and con's between two- and three blade props? Also what is best: rounded blades or blades with a sharp and straight back edge?

Well - I guess this is going to get "scientific" - but please giv me your best and simple advices.

Happy New Year!

Woodie.

NB! I had a look at Propworks West and found this configuration:
6719/3
Just numbers to me. But I'll try to guess:

67 is the diameter?
19 is the pitch according to diameter as 1.9 x diameter?
/3 is the number of blades?

Please correct me if I am wrong.