Bow plowing at high speed.

[sms986]

I did some more looking last night and it looks like it is almost positively from the bunks... the center of the hull under the outboard is fine and the chines are fine. The hook on each side gets worse going toward the bunks from the center or the outside on both sides and there's a very slight crease where the bunks end. I'm going to try to stabilize/support the boat from the transom and press the hooks out from the inside with a bottle jack.

 

[Captain Caveman]

When the boat is on the trailer being towed, are transom tie downs used to keep the boat from bouncing on the trailer? What about a transom saver - which transfers the energy of the motor bouncing from the transom to the boat trailer frame?

 

[sms986]

Yes the transom is strapped to the trailer. Maybe motor bouncing wasn't the right description. What I meant was that the trailer, boat, and motor will bounce on the leaf springs. That's a lot of up and down momentum on the transom from the weight of the motor, tied down or not. Maybe a transom saver would help, but only so much.

Anyway, I took a better look (again) in the daylight. At this point I'm done taking better looks. I'm sick to my stomach as I paid $7k and got a junk boat. The port side has a hook extending about 8" from the transom forward. It extends from just below the outer chine to about 8" from the center of the boat. 1/4" deep at most. The starboard side has a massive hook that extends from the outer chine all the way to about 4" from center. This hook is more than 3' long from the transom forward and 3/4" deep. I took the boat out again and tried anything possible to get it to handle. It didn't work.

Is there any way possible to at least mitigate this? I can't get to the hook on the starboard side as there is a bunch of welded in stuff in the way.

 

[JimS123]

I'm gonna stick to my last comment. I don't think it was the trailer, per se'. It IS a big issue, though.

If it were wood or glass, the hull could be faired. I don't know what to do with aluminum. Looks like the hull has poor integrity, so a fix may be useless anyway.

Try an aluminum fab shop and see what they say. If a fix is not practical, just keep the speed low, adjust the trim up and adjust the motor's trim tab (on the back of the AV Plate to counteract propeller torque at the elevated motor trim.

 

[sms986]

There is a fresh weld extending from the transom about 3' up on the starboard side of the boat. I know welding creates some pretty intense heat and aluminum loves to transfer it. It may be possible that welding the boat on the trailer may have caused the huge hook on this side. The other side has the crease at the end of the bunk, but this side has no bonks or dents. Just a big smooth hook.

I would be fine with going slower than full speed, but anything over 15mph felt like a wild bull ride. The thing was all over the place when I tried to turn. It would plane and the bow would stay barely out of the water until 3/4 throttle, but I couldn't turn without feeling like I was either sliding around or going to roll. Sometimes the steering would be easy and sometimes it took everything I had to turn it. Honestly, after 1/2 throttle the trim had absolutely no effect at all on the steering or bow rise. I could pull it all the way up and it would just gurgle for water, but the bow didn't dare go any higher no matter what. I even had 2 grown men sit on the rear deck with me and that didn't do anything. It's like a magnet on the water. I had it out for 4 hours today just driving around and trying desperately convince myself it was me and not the boat. Even though I've never had a "bass boat" like this, I have driven so many boats of different shapes and sizes. This is not normal.

 

[TyeeMan]

You will only be able to trim up so far as your trim limiter will stop the motor from trimming any farther. If at any time your motor stops peeing shut it down immediately! That's the indicator that says your water pump is working. You want a nice strong pee stream at all engine rpm's

 

[vroom ZOOM]

Now I throw in my 0.02.

1. the hook in the hull. Pull up the floor and have a look at the stringers. If the hook is not intentional in the hull (i.e. not part of the boat design) and is damage, then it will be pretty evident. Aluminum usually cracks when it bends, (don't ask me how I know). The stringers will crack lengthwise along the bend where they meet the hull, like this:


2. The motor bouncing. Trim the motor up and grab it by the lower unit. Yank it up and down and see if the transom moves, or it is just the trim and tilt unit. If it is the trim and tilt, top it off with some fluid, and run it up and down to clear the bubbles. If it is the transom... you are in for a lil' bit of fun.

3. The motor on the lower hole. ugh. . That is not necessarily a good thing. More likely bad than good. What you need to do is have someone drive the boat at cruising speed, and then go look at the back of the boat and see where the water is flowing relative the the anti ventilation plate (the large plate above the prop). The plate should just be skimming the surface, if it is buried underwater, it could be causing the nose to plow, or if it is too high, you might overheat your engine. Checking your engine height is the first thing I would check before spending money. It may very well fix your problem.

4. running 50 with a 90 on that boat is pretty good. (especially with a buried engine). If you were seriously nose plowing you would not get past 40. Check your speed with a gps. Something does not add up.

Many aluminum boats will vent the prop (i.e. prop will lose grip and engine rpms will go sky high) before the boat begins to porpoise. In other words, keep trimming until the bow begins to bounce, or the prop loses grip, then trim down a touch. This is your ideal running position.

 

[vroom ZOOM]

I looked at the pics a second time, and a familiar damage type came up. Whatever idiot owned the boat before must have been powerloading it pretty hard. Happened to my boat when I bought it, exact same thing, except in mine the damage was more localised. It does not affect the performance on mine though. Each time they loaded up they were ramming the boat hard into the trailer bunks, and over time it bent the area in where the bunks are.

 

[LundAngler1650]

I know this doesn't help you now, but never ever buy a boat without an in water test. Although I am only an auto tech, not marine mechanic, I have worked on many boats for people, and been asked to look over dozens of boats for people who are thinking about buying them. I refuse to do an on land only test, I tow it to a boat ramp, launch, and run it as it will be used in real life. Amazing how often that exposed big issues. 90% of the time it was in a river, because a river runs right through town, where a lake would require a lot longer tow. About 1 in 3 boats I told the people not to buy it. Sometimes I said buy it if you want, but here is a list of things that you need to get fixed, so negotiate that price. But definitely always do an in water test.
Now first thing is to get that trailer adjusted so the boat is further ahead, instead of continuing to make it worse. Also there is no need to strap the stern down to tightly. Do the rear straps up just snug, don't be yanking on them like a gorilla.

 

[LundAngler1650]

I looked at the pics a second time, and a familiar damage type came up. Whatever idiot owned the boat before must have been powerloading it pretty hard. Happened to my boat when I bought it, exact same thing, except in mine the damage was more localised. It does not affect the performance on mine though. Each time they loaded up they were ramming the boat hard into the trailer bunks, and over time it bent the area in where the bunks are.

Yikes!

I back my trailer in until a gentle nudge pushes my boat off when launching. When retrieving the boat doesn't touch the bunks until mid way up the boards, and i am going slower than walking speed.

 

[sms986]

Ok guys, here's some stuff.

First, I want to clarify, the motor is not bouncing. I shouldn't have said that. What I meant is everything bounces on the suspension when going over bumps-totally normal but if the bunks don't extend past the transom then no good.

I did move the winch and jack forward so that the bunks go 1" past the transom. That's as much as I can move it forward. Changing them out with longer 2x6 bunks later this week. I also got a transom saver.

The boat will not porpoise at any speed. The motor goes up until roms suddenly change and I feel a change in the ride, then I drop it down just until the rpms settle and cruise.

Clocked it with a gps and I can hit 43. I was way off. Cruising safely at about 30.

I am not having problems with the pee stream. The motor "gurgling" is referencing to what @vroom ZOOM said. I'm venting the prop with no bow lift at high speeds.

The hooks can't be intentional because they are not even close to the same shape and size on either side.

When I trailer, I don't even use the motor. I pull the boat onto the trailer with the anchor rope and then the winch, and it's always just hardly afloat when I lock the winch and pull it out.

I should have lake tested it, but the nearest lake to this guy's place was an hour's drive.

Taking it to a repair shop to see what they say tomorrow.

Thanks for all the help and advice guys, I'm starting to feel a bit better about this.

 

[LundAngler1650]

30 mph cruise is not a bad speed.
Hopefully it all works out okay in the end

 

[Maclin]

I looked for references to the question I am about to ask and did not see the subject raised. But... how does it behave when turning at speed, say 30+ ? Does it plow? or does it lean into the turn appropriately?