maiden voayge yesterday, 2 things i need advice on

[turbocorrado]

so it went pretty good, no serious issues aside from getting stuck in mud. but there are 2 issues i encountered
1. after a full throttle run i was slowing down and taking a turn, between 1500 and 2000 rpms, and it seemed like it popped out of forward for 2-3 seconds but then re-engaged on its own with a slight jerk forward as it did, im assuming i just need to adjust the shift cable so that it engages in forward slightly more. it only happened 1 time during the whole day

2. engine is a mercury 4.3, redline iirc is supposed to be 4400-4800 (which btw, what does that mean. why dont they give an exact number?) at full throttle its only pulling 4k rpms. is this a prop or throttle adjustment issue. its an alpha 1 gen 2 and the current prop on it is a 14.5 x 19

 

[Bondo]

so it went pretty good, no serious issues aside from getting stuck in mud. but there are 2 issues i encountered
1. after a full throttle run i was slowing down and taking a turn, between 1500 and 2000 rpms, and it seemed like it popped out of forward for 2-3 seconds but then re-engaged on its own with a slight jerk forward as it did, im assuming i just need to adjust the shift cable so that it engages in forward slightly more. it only happened 1 time during the whole day

2. engine is a mercury 4.3, redline iirc is supposed to be 4400-4800 (which btw, what does that mean. why dont they give an exact number?) at full throttle its only pulling 4k rpms. is this a prop or throttle adjustment issue. its an alpha 1 gen 2 and the current prop on it is a 14.5 x 19

Ayuh,.... #1,.... I'm guessin' you were turnin' too sharp, or too fast, 'n ventilated the prop, once it found clean water, it hooked up again,....
Pullin' back, 'n pushin' the throttle usually aids hookin' back up,...
Or don't turn so sharp, 'n fast,......

#2,... Either the motor is down on power, or it's over-proped,...
Has it Ever ran 4800 rpms for you,..??
Did ya trim up, to loosen the hull,..??
There Wot range is a window, 'cause hull loads, 'n water conditions vary, ya prop to run In the window, at Wot,....

 

[ziggy]

after a full throttle run i was slowing down and taking a turn, between 1500 and 2000 rpms, and it seemed like it popped out of forward for 2-3 seconds but then re-engaged on its own with a slight jerk forward

could be as simple as the prop blowing out (becoming disconnected with the water) in the turn. or, prop hub could be slipping. to find out, scribe the prop shaft and the prop. run it and see if the lines are still lined up after the run. or, maybe the coupler starting to fail. ya may smell rubber burning or see rubber thats come off the coupler in the bilge. with this condition, if the coupler fails, it will overheat too.

engine is a mercury 4.3, redline iirc is supposed to be 4400-4800 (which btw, what does that mean. why dont they give an exact number?)

that means the engine revolution per min. (rpm)are supposed to be between 4400 rpm and 4800 rpm. this is what the mfg recommends for a long lived engine. over or under and the engine isn't performing proper for some reason. so at your 4K rpm, your 400 rpms under mfg specifications. one fix could be repropping to a lower pitch prop which lets the engine wind up more. or maybe ya just need a tune up. or maybe your engine isn't healthy. a compression test is a good place to start to see if that's the case.

 

[turbocorrado]

it was my first time ever out on the boat so i have nothing to base anything off of as far as if its ever ran to 4800 before
i know what rpm stands for haha, i was just curious as to why its a range and not an exact number like a car.
i didnt think i was turning to fast or sharp, but its a possibility, like i said it was my first time. i figured if it was a shift cable issue i would have had multiiple issues with it. i know the prop hub looked like it was starting to blow out, there was rubber squeezing out when i bought it. guess when i get a new prop il get a new hub as well

also, i trimmed up, at first 4k rpms was about 32 mph, i trimmed up a bit and got it to 36-37 mph and almost to 4100 rpms

 

[turbocorrado]

i may still adjust the shift cable some, i was getting some grinding when putting it in forward

 

[Dave-R]

The grinding noise is normal for a mercruiser alpha. They have what is called a dog clutch. You want to quickly put it in gear,and not slowly which can grind the dog clutch. They work well actually, I don't think you have an adjustment problem, but a learning curve. Dave-R

 

[DaveG55]

I really doubt you need to adjust the shift cable. You don't describe the jumping out of gear incident very clearly but, like others, it sounds more like you pulled the prop too close to the surface.

Marine engines have a wot range because any given boat can be tasked for different uses, ie cruising or watersport towing or speed, etc. WOT is designed to take advantage of the engines power curve. WOT is not the same as an automobile engines redline.

Since we only know your engine/outdrive combo and not your boat its hard to determine what might be the problem. Overall weight, hull material, hull design, outdrive gear ratio and water conditions among many other factors all make a huge difference in what actual wot will be.
I do wonder, from your posts, how agressive you are being with the trim at wot. You should be pretty agressive. What I do is, with the fuel between full and about half full and me on the boat, I fibd a good stretch of good water (a light chop is better than mirror water). I then push onto plane then to wot. I then trim the outdrive as high as possible keeping an eye on the tach, right up to the prop losing its grip. After noting where the trim guage is set I then bump the trim down until it grabs again. At that point I trim back up to just before where the prop lost its grip. Now check the tach a final time. Thats you wot rpm. While your atbwot, see what the speedo says your speed is.

A couple of rules of thumb when considering props.

1 inch of pitch equals approximately 100 wot rpm.

Increasing pitch lowers wot rpm, decreasing pitch increases wot rpm

Increasing pitch increases top speed at the expense of holeshot.

decreasing pitch improves hole shot and time to plane at the expense of top speed.

Many other prop factors such as cupping, material, number of blades, rake, venting and diameter all affect wot and prop preformance.

​If you decide you need a prop then I highly reccomend doing a search for prop selectors and plug in your information.
​Good luck.

 

[turbocorrado]

I really doubt you need to adjust the shift cable. You don't describe the jumping out of gear incident very clearly but, like others, it sounds more like you pulled the prop too close to the surface.

Marine engines have a wot range because any given boat can be tasked for different uses, ie cruising or watersport towing or speed, etc. WOT is designed to take advantage of the engines power curve. WOT is not the same as an automobile engines redline.

Since we only know your engine/outdrive combo and not your boat its hard to determine what might be the problem. Overall weight, hull material, hull design, outdrive gear ratio and water conditions among many other factors all make a huge difference in what actual wot will be.
I do wonder, from your posts, how agressive you are being with the trim at wot. You should be pretty agressive. What I do is, with the fuel between full and about half full and me on the boat, I fibd a good stretch of good water (a light chop is better than mirror water). I then push onto plane then to wot. I then trim the outdrive as high as possible keeping an eye on the tach, right up to the prop losing its grip. After noting where the trim guage is set I then bump the trim down until it grabs again. At that point I trim back up to just before where the prop lost its grip. Now check the tach a final time. Thats you wot rpm. While your atbwot, see what the speedo says your speed is.

A couple of rules of thumb when considering props.

1 inch of pitch equals approximately 100 wot rpm.

Increasing pitch lowers wot rpm, decreasing pitch increases wot rpm

Increasing pitch increases top speed at the expense of holeshot.

decreasing pitch improves hole shot and time to plane at the expense of top speed.

Many other prop factors such as cupping, material, number of blades, rake, venting and diameter all affect wot and prop preformance.

​If you decide you need a prop then I highly reccomend doing a search for prop selectors and plug in your information.
​Good luck.

sorry, thought i put the boat info in 1st post. boat is a 1997 wellcraft eclipse. 20ft bowrider, engine is a 4.3 that was put in around 2006, outdrive is a alpha 1 gen 2. not sure on what ratio it is. i had 4 people total plus gear on it. with trim almost all the way down, 4k rpms was 32 mph, i trimmed up until i got to 36-37 mph, and rpms went to ~4100...trimming up anymore seemed to lose speed so i backed off. i know my prop is pretty worn and not perfect, but i dont wanna buy the same prop again and have no improvements, i also dont want to drop to a 17 pitch to get my rpms, but lose top speed, as 37mph is to low anyway.

a pic of the prop after the run on sunday