290DP Props, what do you think?

[vstol]

Hello All,<br /><br />I have a 290DP Volvo Penta w/ 431A motor on a 19.5' stingray. When I got the boat it had B7 props on it. But they had to be cut off due to corrosoin, some of you may remeber that thread. I have noticed with the B6's I have put on it since then the out of hole performance is a little better but obviously the top end is lacking a little. wide open throttle is suppose to be 4600-4800 I think. I can not even get the 4 barrels opened up with the B6's that are on it now or it will overspeed, to be expected i guess. The point is that I am ordering a new set, I think that these that I have are so worn down by that I mean thin (really minimial damaged other wise and that has been blended out) that they are flexing more than a good set of B6's would. I am not sure how old the B6's are I just know they are really thin compared to some other alumium props i have seen and seem to nick or tear really easy.<br /><br />Finally the question, I am defintly going back to at least a B7, what would be the draw back to going up to a set of B8's other than loosing a little coming out of the hole.

 

[Limited-Time]

Re: 290DP Props, what do you think?

If there is too much pitch your engine will not reach the correct wot rpm. This condition will over load the engine and lead to damage due to heat and or detonation. You also loose on both ends as thr engine never reaches max rpm.

 

[vstol]

Re: 290DP Props, what do you think?

Thanks for the input but I am afraid I don’t speak prop very well, I may be prop-retarded even, could someone elaborate please and if you could explain is it the b7 set or b6 with more pitch, what does pitch have to do with it, I understand vaguely but not fully.

 

[tommays]

Re: 290DP Props, what do you think?

http://www.mercurymarine.com/everything_you_need_to_know_about_propellers5 <br /><br />this is good reading and should make things clearer<br /><br />you allready no what happens when the props to small but haveing a prop thats to big is BAD because it will over load the motor<br /><br />if you give your current speed and RPM don,s or rodbolt are volvo pros and can give you much better advise on duo props<br /><br />tommays

 

[vstol]

Re: 290DP Props, what do you think?

Thanks for the info, If Don,s or rodbolt is reading today I had it doing 42mpg by my GPS, speedometer said 52, i am going with the GPS. What do you guys think?

 

[Don S]

Re: 290DP Props, what do you think?

If you are getting in the range of 5100 or 5200 rpm at WOT right now with the B6 set, you should go up in pitch to the B7 set. It will slow your rpm down approximatly 400 rpm per size. Just make sure you are doing your tests with a NORMAL load, that way if you get a little heavier, or lighter load you're still in the general area.

 

[tommays]

Re: 290DP Props, what do you think?

 

[vstol]

Re: 290DP Props, what do you think?

How important is it to really watch the RPM, I do it now alot because I know I can over speed with the B6's but with B7's, which I believe are stock, how often do I need to watch. Once I test it under a full load (8 people and some coolers along with full tank i gas i assume) do I just listen after checking initially. I really keep my eye on it now and it is taking away from the fun a little. Also Don,s what do you think about my prop blades being thiner than most, does this really happen how, can they get thinner or do just the ends get thinner with blending?