Lots of info within:
http://www.volvopenta.com/SiteCollec...er%20Guide.pdf
Note: Within above .PDF file, focus on Page 8 & Page 9 -> for Volvo 280s.
Recommend to pick the "pitch" in the middle range (of their tables) and go up/down for 2nd prop - depending on boat's hull shape and loading. And, if you want a hole-shot prop or a high speed prop. This will give you a "starting guess".
Then, using iBoats,com store, search their inboard Volvo engine prop section and pick the best guess prop you think you might need - for your specific engine / unique setup. Recommending buying 1 x prop 1st and give it a try - based on your engine's max RPM at WOT tests. If you want more hole shot, buy another prop with less pitch. If you want faster WOT speed, then go 1 x pitch higher. The previously bought prop then becomes your spare (or alternate usage) prop.
My 17ft Bayliner bowrider boat has 2 x props. My main prop and my spare / alternate usage prop. My main prop is 4 blade 15 pitch (which feels like a 3 blade 17 pitch with more grip). And my spare prop is a 3 bade 17 pitch. The 4-bade is great for water sports or heavy weight loads. And the 17 prop is better for long distance mid range RPM cursing conditions. When needed, I'll swap props - before doing an outing. But my main prop is the 4-blade (which my boat likes much better for stern lift as well).
Due to boat's hull design, different weight loads, needed stern lift, etc. etc, there's no "1 x perfect prop" for all. Each boat (even for same engine) is unique. Thus, different size prop for different folks. Thus, best to guess for the 1st prop and 2nd prop purchase is up or down (based on results of 1st prop usage results).
Hope this helps.
