Shudder at surf speed

[somebodyelse5]

Boat has been shuddering during surfing when all the ballast is full, 1100# in locker, 300# up front, plus 2 400#'s (one on the seat one on the floor)

Could there be a bushing out on the shaft support?


Also does it when unweighted and at higher speed. Could it be rudder vbration??


Thanks guys.

[chpthril]

Sounds like prop cavitation. What prop are you running.

[ragboy]

y, new prop should solve that.

[somebodyelse5]

Sounds like prop cavitation. What prop are you running.

prop is a 4 blade ACME 537

[chpthril]

prop is a 4 blade ACME 537

Outside of a tweeked blade, you are probably reaching the limits of the 537 due to the added ballast.

[bryancm]

I get a similar, faint intermittent shudder at surf speeds when weighted down (mine does not shudder at higher speeds and when unweighted). I have a 3-blade Acme 515 (13.00dia, 12.00pitch). Could the prop be the culprit here as well?

Thanks!

[somebodyelse5]

Outside of a tweeked blade, you are probably reaching the limits of the 537 due to the added ballast.

Mike whats the next prop up? Might need to get one from you next season, this seasons pretty much over other than a few outtings here and there when im back for the weekend. Classes started back up today...

Could part of it be my tranny slipping? With the lean and bow rise, if the fluids low it could mean minimal lubrication....may not be the whole issue but i have a feeling its part of it.

When surfing with the weight we have trouble getting up to 11.5mph with the taps at 6, lowering taps minimizes shudder and allows us to get up to speed. when it shudders, its an obvious power loss. like if you were driving down the free way and pushed in the clutch for a second for a second...

[chpthril]

I get a similar, faint intermittent shudder at surf speeds when weighted down (mine does not shudder at higher speeds and when unweighted). I have a 3-blade Acme 515 (13.00dia, 12.00pitch). Could the prop be the culprit here as well?

Thanks!

High probability. I would recommend calling ACME and giving them all your info about the boat, how you primarily use the boat and how much weight you run. They will make a prop recommendation. Let me know what the suggest and we will see what we can do.

Mike whats the next prop up? Might need to get one from you next season, this seasons pretty much over other than a few outtings here and there when im back for the weekend. Classes started back up today...

Could part of it be my tranny slipping? With the lean and bow rise, if the fluids low it could mean minimal lubrication....may not be the whole issue but i have a feeling its part of it.

When surfing with the weight we have trouble getting up to 11.5mph with the taps at 6, lowering taps minimizes shudder and allows us to get up to speed. when it shudders, its an obvious power loss. like if you were driving down the free way and pushed in the clutch for a second for a second...

The most popular upgrade for the 537 is the 1235, but lets make sure you have the 1.5:1 gear box just to be sure.

Trans slip is a possibility, are you seeing or noticing the engine revving up at the same time? If the 537 is the correct prop, there is no doubt that the weight you are running will be pushing the limits of that prop. We got it all the time on our 22Ve when loaded down and the water was choppy.

A prop swap (or the correct) will also help hole-shot and getting up to speed.

[somebodyelse5]

High probability. I would recommend calling ACME and giving them all your info about the boat, how you primarily use the boat and how much weight you run. They will make a prop recommendation. Let me know what the suggest and we will see what we can do.



The most popular upgrade for the 537 is the 1235, but lets make sure you have the 1.5:1 gear box just to be sure.

Trans slip is a possibility, are you seeing or noticing the engine revving up at the same time? If the 537 is the correct prop, there is no doubt that the weight you are running will be pushing the limits of that prop. We got it all the time on our 22Ve when loaded down and the water was choppy.

A prop swap (or the correct) will also help hole-shot and getting up to speed.

engine revs up pretty high, almost 4k rpm if i remember correctly. isnt the color of the drive conducive to whether it is the 1.5:1 or the 1:1? the drive is painted blue if that helps at all.

[chpthril]

engine revs up pretty high, almost 4k rpm if i remember correctly. isnt the color of the drive conducive to whether it is the 1.5:1 or the 1:1? the drive is painted blue if that helps at all.

Blue is the Walter 1.5:1 gear, so the 4-blade 537 is the correct prop. I would call ACME just to make sure that the 14.5 diameter of the 1235 is not going to be a clearance issue with the 20V hull.