Properly Proped at Last - H450

[Bob Bass]

We have a H450 with the 63hp turbo Yanmar. The factory installed the wrong prop, a 17x11. I was spinning my wheels and going nowhere. Max rpm was somewhere over 4000. Hunter engineers recalculated and then installed a 18x16. Then I started noticing more smoke and at rpm over 2900 diesel fuel would collect on the bottom step of the swim platform from the exhaust. The max rpm was 3200 and as soon as I went over 2600, the temperature would start to climb a little. Yanmar said that the engine needed to be run at the high rpm and that I should be able to max at least 3600 and that I was lugging the engine. I had the prop repitched to 18x14 and this is just right for my boat. Max rpm almost 3800, no temperature rise at high rpm, almost no smoke, no disel fuel in the exhaust, and very little loss of speed. The max rpm will probably drop a little when I am in cruising configuration (loaded with beer and towing the dink). I have heard others talking about a smoking problem and a change of pitch might solve it. It will also mean longer engine life, better fuel consumption and will keep the turbo from fouling. A pitch of 18x15 might work for a H450 of less weight and not towing a dink. Are other H450 owners experiencing this?

 

[Gordon Myers]

Interesting - What is your speed / fuel use

We are buying a new 450. Very interesting. Do you know what your speed is and do you have an idea what the gals. / hr. are ?

 

[Chuck Wolfe]

Hull Speed and Autoprop

If I could afford or want a 450 I would put an Autoprop on it. Then you don't have to worry about stuff like this. Run it in gear at the dock and it should get to the max rpms recommended for the engine. Then take it out and don't pay attention to the rpm's, just the speed. Once you get near hull or at hull speed, giving it more throttle doesn't give you more rpm's, only black smoke because then you are overloading the engine. I discussed this issue with Yanmar. They are putting these things standard on Swans and Baltics. It's an amazing prop in my humble opinion. chuckwolfe@mail.com

 

[Bradley Cavedo]

We have 17x15 on P42

We have the same engine on a lighter boat, P42. A 17x15 two blade folding prop. We could take a 18x15, but 17 is the biggest prop Flex-o-fold makes. We can max out at 3800 and we cruise at 3000 to 3100 and have no smoke. we cruise at 7.8 with clean everything. Hull speed is about 8.0

 

[Bob Bass]

Reply to Gordon Meyers

We only ran the boat for just over an hour after the pitch change. Speed was by GPS and was around 7.5 at 3000. Fuel consumption is to be determined, but will probably be better than before.