Will this prop spec work on my boat?

Performance cruising sailing cat with 2 engines. 8000kg 18,000lbs loaded. 43 foot.

Yanmar 3GM30 27hp @ 3600rpm. SD20 2.62:1 ratio.

Props that I can get cheap = 3 blade flexofold 18"D x 11.3P

Will it work OK, the prop is bigger than what most calcs recommend, but it also has less pitch? My prop guys says its one inch bigger than his calcs say, but also has less pitch so its worth a go?

Thoughts?

 

I am not a Naval Architect and I,m not sure about catamarans. But an 18000lb mono displacement hull with 54 Shp will do about 8.4kts. A a semi displacement cat about 9.6kts. A 27hp motor can run an 18.4" prop, 10.5 inch pitch is required for 8.4kts on a mono hull. There is a minimum prop dia for a mono hull but I don't know if it applies to cats.

In conclusion I think 18D x 11.3P will work and you could get about 8.75kts.
Hope this helps Mik

 

I just ended up putting the volvo folding props back on. Does about 9K full speed. Cruises at 7-8.