PQ290Enticer

Bummer. If even one was slipping it would explain everything and is a cheap fix. Try posting a vid. Might be what someone needs to properly diagnose your situation.

SammyJ

Check your trim cylinders... compare the colapsed length of what you have to a new cylinder..........
I had a Banana Boat in the 70's with a big block / TRS setup, a merc dealer put new trim cylinders on it one summer and after the install i had the same issue as you, boat accelerated like drive was trimmed out,
***** part, it was trimmed out, fully retracted the new cylinders were 1" longer than the original cylinders, the dealer installed the wrong ones
Got those pulled and put original short trimcylinders on and problem disappeard

PQ290Enticer

Dbl post

baja 33outlaw

I hope it's something kinda simple and straight forward like that, I'll definitely check that and take pictures of what everyone has told me to check out.

Also apologies to it taking so long, and seemingly not following through with advice here yet. The boat is an hour away, and haven't had a day off work since I've posted this to go pull it out and take some pics.

I do have a video from about a month ago, I'll put it in the next post. Gotta go upload it to YouTube real quick.

baja 33outlaw

Here's a video from a bit ago that kinda shows what happens. I usually don't try to take off this aggressively, but it's the only video I have for now.

So I start from idle speed, then push throttles about 40% the boat initially takes off how it should for about 2-3 seconds. In the video I do not move the throttles at all until I lower them back to idle. With the throttles at around 40% rpms go right to 2500rpm, when you see the rpm shoot up that's when the boat has lost all its momentum and seems the props are "washing out". The throttles were not touched until it was about to hit 4000rpm, at that point I lowered them back to idle.

Hopefully I explained it well, thanks for helping me try to figure this out.

Brad Christy

Baja33Outlaw,

That's a tried and proven hull, and, as I understand it, those are the right props. Has anything been done to the drives? Damage? Repaired? Do you have any pics? What's the bottom of your hull look like? It almost sounds like something is feeding the props cavitation or your drives are just too high. If you've got the "celery stick" insert (#30 in the exploded view), and it's in backwards, it can cause your drive to be too high. If they've been worked on, this is a possibility.

BTW, Your video looks and sounds a lot like our PQ280 after I "found the bottom" on Cumberland and did some minor damage to the prop. Prior to, the boat would take off and plane without even so much as a minor slip. Now, as the boat noses over, the prop will blow out slightly, and, if I don't feather out of the throttle, it will totally blow out, but it will still hold enough traction to get on plane. The timing is a little later than yours, though.

Curious to see what the issue is, though.

Thanks. Brad.

baja 33outlaw

No repairs or issues with the drives, that I know of, but the boat had about 750hrs on it when I bought it. So wouldn't doubt they've been repaired at some point. Hoping to pull it out this week so I can get some pictures, if I can get a day off work. Unfortunately I leave the boat in the water, so the bottom is currently pretty dirty, but when clean it still has issues planning. Kinda like you said with your pq280 slowly feathering throttles. The new 26p props I put on were slightly better, but it still had to be feathered to get going. Maybe they were also fighting themselves since at top speed one was at 4700 while the they was around 4250rpm.

The video was when I first put it in with a clean hull. It had this problem when I bought the boat, but figured that it was normal. Also on the water test, I only rode passenger and didn't realize why he babied it to get on plane. Previous owner kept the boat on a lift, I'll add that Pic just to show the boat condition. Also found a picture when I bought it of the back, kinda showing the drives probably doesn't quite show enough though.

PQ290Enticer

Just my opinion but i think you are rushing the process based on your video. Leave it at 2500 till the bow starts coming down. Then slowly add throttle and trim. You will be able to fine tune as you get more seat time.

Brad Christy

Baja33Outlaw,

Might be a forced perspective thing with that first pic but, check the alignment of your drives for parallel. I don't know if I've ever heard of a shop doing something so dumb, but that does not look like a stock OEM steering setup, and it certainly looks like they are not parallel. You're gonna want to get a dimension from the bottom of the hull to the C/L of the prop hub, too. I can't tell you what than number should be, but others can, and the fact that it would appear someone's fiddled with things, they may have put a shorter lower on the outdrives than should be there, making them run high. Or trim rams that are too long. Or that celery stick on the wrong side. Or..... Or.....

I don't think having the engines out of sync would cause such an issue at takeoff, but others might have relevant experience to say it could. One does wonder what is causing it, though. If it DID contribute to it, I'd think one prop would blow out before the other, and it doesn't look like that's the case in the video.

There are plenty of those boats out there, and they all run fine. You just gotta figure out what someone's done, for whatever reason, and correct it. It's always the stupid sh!t. Sucks for you, but I love puzzles. Even if I'm not the one that solves them.

Thanks. Brad.

Brad Christy

Baja33Outlaw,

Also.... Can't tell in the video.... Do the props blow out before the nose starts over, or while it's still climbing/nose high? Judging by the timing, mine would still be climbing upward, not even thinking about nosing over yet, when your props blow out. And the fact that they are synced in time of occurrence indicates to me that it's not something related to the engines, drives or props, unless something specific was done to both of them. Get a good look/feel at the bottom of the hull for stress cracks and anything that is not smooth. Look hard at the individual parts of the drives. It there's anything not OEM, it/they would be suspect #1 for me. Everything I'm seeing is screaming "too shallow" to me.

Thanks. Brad.