macroft1 Posted August 19, 2015 Share Posted August 19, 2015 The propeller on my Yamaha 9.9hp 4 stroke outboard has seen better days and I'm looking to replace it.It pushes my Norman 18.5ft and I know you can get different pitches and high thrust etc. but I don't know enough about them to make a decision.Can anyone advise me on what I need?Regards.Mark. Quote Link to comment Share on other sites More sharing options...
Viking23 Posted August 19, 2015 Share Posted August 19, 2015 Have you looked at the Norman Boats Appreciation Society, there must be something on there... if not, an interesting forum to join. http://www.normanboats.co.uk Quote Link to comment Share on other sites More sharing options...
Wildfuzz Posted August 20, 2015 Share Posted August 20, 2015 I changed to a four bladed prop on my 15 HP on a 20` boat, kept the revs within the engine guide lines and gave much better control at lower speeds and in reverse. It can be a minefield if you are considering changing pitch or diameter but loads of info available. Rule of thumb is if you increase the pitch by 1" you drop the maximum revs by 500 rpm and the opposite if you decrease the pitch. Four blades gives much better lower speed handling with no loss of top speed. Ideal for rivers and low speed limits. I got it from Steel Developments (on the web) they were very helpful and informative. 2 Quote Link to comment Share on other sites More sharing options...
ExUserGone Posted October 5, 2015 Share Posted October 5, 2015 When I had an outboard powered boat I went down the 4 blade route and also found it much better for low speed manouvering with no loss of power at full throttle, stainless steel developments is where I went for the new one. Quote Link to comment Share on other sites More sharing options...
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