I am currently installing a Volvo aq 290 ie 5.7 litre V8 with 290 single prop drive ratio.1.61/1
Any one know what size propeller either 3 or 4 blade

Can any body in this club read English or translate
This is the second time of posting on here and getting no response with this and not being informed about insurance through club NOT available to UK members untill I joined !! Does not inspire me to renew my membership!!

Hi Peter
No reason to be rude if you don't get any response on your posts for a few days. This is an open forum where members and non members "discuss" various matters, not the CYC.

Regarding the insurance it's quite easy to read the information on the page regarding membership that :
"Our unique collaboration with Atlantica Insurances allows Danish and Swedish members to lower your insurance costs significantly each year."

Me and many others here do understand English, often reply on questions in both swedish and English. But if I don't have any experience of what you're asking I cannot give you any useful information.
The only thing I know about SP drives from the few I have ever been riding four blade seems to be optimal for at least low powered engines. Everything from 4.3 L and up I only had DP units.
Props are quite complex and a lot of factors included, but just size or gear ratio.
Don't you have any propeller shop or mechanic in the UK? The ones we have available in Sweden are great at helping out and have so much experience.

Good luck finding the right prop!

http://www.thestraycat.net/files/Volvo%2520Penta%2520Owners%2520Manual.pdf

On the last page you have the VP recommendations for original three blade props.

Propeller choise is highly dependent on preferred performance, acceleration usual load - try this calculator: https://www.mercurymarine.com/en-gb/europe/propellers/selector/#!/step-one
(I know its intended for Mercruiser).

https://www.mercurymarine.com/en-gb/europe/propellers/selector/#!/step-one

By the way, I'm having a 19" High Five, mounted on a Alpha Drive 1.47:1 and a Merc 5.0 MPI (260 hp).