Vexus w/ evinrude 150 g2 ho prop for high altitude?

[CarlB]

I have a new Vexus AVX 1980 with the Evinrude ETEC 150 G2 HO engine. 6" manual jack plate. I am at roughly 4500 altitude. Looking for a starting point for props. I believe I have a 24p (stock evinrude prop) now, and as I was trimming up it seems that about 4800 rpm/45 mph I start to loose speed as I trim up farther. This was full fuel and tackle, only me in the boat and about 75 air temp, smooth conditions. Pretty sure that is too much prop for this altitude, thinking a 22 might be closer, but before spending the money I wanted to make sure I am not way off base. Hole shot was surprisingly good, so it might be a motor height issue, but my mind says that is too much prop for this altitude. Will most likely buy a new prop (Mark's best choice?) and then dial it in from there, and send the old one in to be worked for a spare/low altitude prop. Any insight appreciated it has been a LONG time since I had to prop a boat.

[mdtritn21]

Too much prop for 4500 ft. the 22 would be a lot better.

[JR19]

I have no first hand experience but from what I have read its your jack-plate that might be causing the issue...G2 motors have a lot of setback built into the motor mount. People who run 250 HP on 21 ft boats only run 4" of setback. Based on what little I know it sounds like your fulcrum point (jackplate) is so far back you can not get enough bite to gain speed at high rpm. I may be way off line on my assessment but this is where I put my $ on what the issue is. I would have my dealer contact Vexus and ask what size if any jack-plate they recommend for your particular boat/motor combination. I bet Vexus will say run a 4" jack-plate or possibly remove your jack-plate and don't run one at all. When the dealer calls Vexus make sure they know your specific particular situation (4500 ft elevation and 24 Raker prop)...I think the combination of elevation above sea level and the extra jack-plate length is whats holding you back from gaining speed at high rpm...again just my opinion. I could be totally wrong

[blkfalc4]

Prop to Pad measurements would help also.

[CarlB]

Thank you for the thoughts. I will check with Vexus but the jack plate is pretty standard on their setups. I will also see about getting the prop to pad measurement this weekend (boat is 100 miles away at my parents house at the lake so it will be this weekend). There were not really any bad habits, no porpoising or anything like that, the boat ran beautifully but the lake was really calm, best possible conditions. Thank you again for the help. If it didn't get any better I would still love the boat, but I can't help thinking there is more performance and efficiency waiting to be unleashed.

[mdtritn21]

At 4500 ft you lose 20% of your HP and getting the rpm's up closer to your max rpm's (6000) will help your motor as your lugging it right now at 4800. From what I've read most guys run 6" plates on the 1980 with any motor. Check your present prop to pad measurement too because that boat doesn't have a pad and you could be running it too high since your losing speed and gaining rpm's at WOT so you may have to lower the motor to gain some speed.

[CarlB]

I got a chance to measure prop to pad. I couldn't get 100% accurate numbers because after I leveled the pad the motor was low enough I couldn't trim it down to level. It is at least 5" below pad, possibly more. I took a couple of pictures. Looks like it is mounted in the lowest hole (as far as motor height that is), and the jack plate is slid up a bit.

What kind of number should I be looking for prop to pad? Seems like 5" plus is quite a bit low if I remember what I read correctly. I noticed the dealer had to limit the tilt range because the seastar hydraulic steering almost hits the transom, so that is another thing that makes me think I might be too low

[jc2bg]

I’m not familiar with that boat, but prop to pad in the 3.5 inch range is common. Anything more than 4 is almost certainly too deep.

[mdtritn21]

With it being an aluminum boat I'd try to get it up to 3.5" at the highest. If you only need an inch or two you can put a 2x6 under the tires to raise it or jack the trailer up if you need more.