Update on my boat issues

[Mook!]

Originally was talkin bout some issues I was having with my boat in this fishing report http://www.bigbendfishing.net/phpBB3/vi ... =4&t=16776 but decided to start a thread over here to continue...thanks again to all who gave input and thanks in advance for more...

So I checked out the tach situation this weekend. Hooked up a new Faria tach and sho nuff I was correct about the old one being inaccurate. At 35mph / WOT, the new one reads about 4950, so just under the power band of 5000-6000 and I assume that confirms the overprop issue (and that Chalk was right it ain't by much)? The number on the prop appeared to be 13x20-something, but the number I think was 20-something is worn and I can't tell for sure what it says. I also noticed that one blade has a very very slight dent at the edge maybe 1/8 inch.

I noticed somehting else for the first time yesterday as well; I noted the alignment of the motor to transom when I had it trimmed out on plane. There is a little "E" Evinrude logo that just about perfectly lines up with a bolt at that level of tilt/trim. Next time I tried a hole shot I trimmed it to as close as possible to the exact same spot, and was able to do a fairly quick hole shot with no listing and no pull to starboard as I was getting before. If I trim it much further down or up then I have those issues, but with the trim in a certain range, no problems and I was able to run a hole shot without touching the steering wheel at all.

Next thing I noticed is that the engine died a couple times in forward idle speed immediately after running WOT on plane for a bit, and seems like it was worse the longer I ran WOT before slowing down. It behaved like flooding. Can anyone make a reasonable connection there? I could crank it back up and idle and had no problems, but it died maybe 3 times when I went in forward idle after running WOT.

Finally, I ran a much lower percentage of the day Monday at WOT than last time I took it out, and ran the GPS the whole day. At the end of the day, I had 16 miles on the trip odometer with close to 1 gallon left in the 6.5 gallon tank.

My questions are, can the tilt / trim situation with the listing on a hole shot be related to the prop situation, and where do I go from here as far as selecting a new prop that will run closer to the 5500rpm target? Thanks again for everone's help!

[tin can]

So I checked out the tach situation this weekend. Hooked up a new Faria tach and sho nuff I was correct about the old one being inaccurate. At 35mph / WOT, the new one reads about 4950, so just under the power band of 5000-6000 and I assume that confirms the overprop issue (and that Chalk was right it ain't by much)? The number on the prop appeared to be 13x20-something, but the number I think was 20-something is worn and I can't tell for sure what it says. I also noticed that one blade has a very very slight dent at the edge maybe 1/8 inch.

I can't imagine a 70 horse turning a 20 anything on your boat. It's probably a 21 pitch. Typically 2" of pitch = 200 RPM, +/-. Drop to at least a 19, maybe even a 17, depending on what prop you go with.

I noticed somehting else for the first time yesterday as well; I noted the alignment of the motor to transom when I had it trimmed out on plane. There is a little "E" Evinrude logo that just about perfectly lines up with a bolt at that level of tilt/trim. Next time I tried a hole shot I trimmed it to as close as possible to the exact same spot, and was able to do a fairly quick hole shot with no listing and no pull to starboard as I was getting before. If I trim it much further down or up then I have those issues, but with the trim in a certain range, no problems and I was able to run a hole shot without touching the steering wheel at all.

If you're getting up better with the motor partially trimmed, you could probably raise the motor up 1 hole. As for the torque issue, if the motor is trimmed all the way down, the bow is being pushed down. This "stabilizes the boat in the water. When the boat is stuck to the water the prop torque is magnified. No boat runs straight. You don't want it to. If you raise the motor it will eliminate some of the torque on the hole shot, but may magnify it on the top end. Adjustment of the torque tab, or possibly just trim position should solve the problem.

Next thing I noticed is that the engine died a couple times in forward idle speed immediately after running WOT on plane for a bit, and seems like it was worse the longer I ran WOT before slowing down. It behaved like flooding. Can anyone make a reasonable connection there? I could crank it back up and idle and had no problems, but it died maybe 3 times when I went in forward idle after running WOT.

A couple of ideas. 1-My old Evinrude wouldn't idle well if it were trimmed or tilted up. The attitude of the motor (trim or tilt) affects the float level and will lean the motor down.
2- Just above idle the timing and vacuum condition changes and the motor transitions from drawing on the low speed jets to the high speed jets. After running WOT,and dropping to idle, the vacuum will drop, and the motor will struggle. Try not coming completely out of the throttle all at once. If that doesn't work, try bumping the choke.

Finally, I ran a much lower percentage of the day Monday at WOT than last time I took it out, and ran the GPS the whole day. At the end of the day, I had 16 miles on the trip odometer with close to 1 gallon left in the 6.5 gallon tank.

Every 3 or 4 cylinder OMC I've ever run got between 3.5 and 4 MPG. You're in the ball park.

[Mook!]

Thanks TC - that's a lot of good advice right there. I wasn't going directly from WOT to idle - I back off to about 1/3 until my wake hits me in the arse and then ease in to idle, but your explanation still makes sense and seems consistent. My point about the gas mileage was that it seemed more normal - last time out I went through > 10 gallons in 20 miles. I'd be somewhat satisfied with anything over 3, which is about what I got.

[tin can]

You're welcome. I'll send ya a bill.

[Barhopr]

where's my prize for the best guess at being a 20+ pitch prop?

[What a mess]

It would be cheaper to get that prop worked on at gator prop about 50 bucks.