Bow plowing at high speed.

[sms986]

So I finally decided to pull the trigger on a newer and bigger aluminum fishing boat. I've been watching craigslist for a while and after being lied to/ripped off time after time on every other purchase I've made, I paid a lot of attention and thought I had covered everything when purchasing this boat. It's a slight vee (probably 8-10 degree) 19' Monark with a 99 mercury 90hp on the back. Everything seemed to check out and I spent a good chunk of change, happily pulling my new boat down the road. Took it out today for the first time and it was pretty good. Startup was fine, idled ok, and went in and out of gear pretty well. Putted around for a good bit to get a feel for the controls. First time I opened it up, it jumped on plane pretty quick and felt good until around 3/4 throttle, maybe 35-40mph. After that, the bow went down, almost like the boat was riding flat. The water spray from the sides was about 1/2 way between bow and stern, maybe closer to the bow. It did go faster, thinking 45-50 WOT, and handled ok, but for some reason it felt awfully strange to me. My old fishing boat (15' mod vee with a 40hp on the back) felt like it was riding well on top of the water, bow slightly up). This one planes well until that 3/4 throttle then feels like the bow sucks back down. Might be because I'm not used to it, but something doesn't feel right, and I don't want to be plowing at that speed.

Cavitation plate is right in line with the very bottom of the transom, and the motor is all the way down (transom bolts in the top hole of the motor mount plate). I tried trimming up, but it didn't see to make a difference. Like I said, bow felt right where it should be at 3/4 throttle, but it sucks down anywhere past. Trim up doesn't make a difference at this point.

There are a few small (baseball size and 1/8" at most deep) dings in the hull, and there is a hook in it about 4 feet back from the bow on each side and extending 1 1/2 feet back, about 1/4" deep max. They look like big dents, but they're pretty far up. I'm really hoping I didn't blow a bunch of money on another headache of a problem boat.

Any thoughts/opinions? Like I said, it isn't slowing down at high speeds, but it just feels like the bow is being sucked back down.

 

[sms986]

Also, this boat is bare. In the back, I have the battery, fuel cell, and motor. Small center console unit toward the stern and both a passenger and I sitting on the rear deck. Only thing toward the bow is a trolling motor (no battery). So weight distribution isn't the problem.

 

[dingbat]

Nothing wrong with the boat.

The bow isn’t supposed to be sticking up in air. Running angles are typically in the 3-5 degree range.

I would be more concerned if a 19 ft. rode like a 15 footer

 

[Chris1956]

You should see a wave coming off the hull at least 3/4 of the way back from the bow. if not the bow is plowing water. Can you post a picture of the hull defects. A hook in the transom area will cause the issue.

Trim the motor up and see if the bow lightens. If not, you may need to raise the motor on the transom a bit.

 

[sms986]

How far do you big outboard guys trim up? On my stern drive cruiser, I don't even touch the trim. I have the outdrive almost completely down and it planes and rides fine. It just feels strange to trim up awfully high.

 

[sms986]

@dingbat it feels like it's riding at 0 degrees..

 

[Chris1956]

Wait, someone said "When in doubt, trim it out"

Trim it until the steering feels light. A lot of cruisers, as you have noted, do not benefit from trim. Your boat, depending on hull style, may benefit a lot or a little from trim.

 

[southkogs]

My Bayliner cruises better with a little up trim. It's a stern drive, but only 19.5'.

 

[sms986]

 

[sms986]

 

[sms986]

 

[sms986]

Like I said, it just feels strange. It's not like the bow is shooting up and then dropping back down. It feels like it gets sucked back down and the boat is riding flat. Had my cruiser out a few times before the restoration , and the bow would go high until it got up on plane, then it would level out and cruise at a nice angle. This feels like the bottom of the boat glues itself to the water. Hard to explain, but it feels very strange to drive at speed.

I'll try to trim up until I don't see the motor peeing and see if that lifts it up a bit. Could just be me, I don't know how far up is acceptable for trim and I'm a bit sceptical after many unfortunate cl encounters.

 

[JimS123]

I had the same problem on 2 different boats. One had a hook in the hull, the other was just over-powered. The hook was at the stern, so I could not find a fix. To fix the other one I just put on a smaller motor (just under the capacity spec) and all was well.

Since your hook is far forward, maybe you have a prayer. Just trim the motor up as high as you can without causing porpoising. You should have no more than 5' of hull in the water when on plane.

 

[sms986]

The boat is rated for 125 and has a 90. Speed is moderate. I have no clue how fast we were going, I'm just basing the speed off of a few boat rides I had in an xpress 22' with a 115 on it.

I'll try to trim or maybe putty the hook if I can.

 

[southkogs]

Rated for a 125 and you having a 90 kinda' puts you on the edge of being slightly underpowered. She might just be kinda' "slushy."

 

[sms986]

You really think so? It went pretty quick. 2 boatlengths to get on plane. Faster than I expected. Hmm, maybe though? I'm new to the big boats.

My dad's mod vee is rated for 50 max and I can plane it by myself with a 9.9.

 

[southkogs]

... it's in the "maybe" column. Like I said, you're on the edge of being underpowered; but not necessarily. Different hulls react differently to that.

 

[Stinnett21]

I had the same problem on 2 different boats. One had a hook in the hull, the other was just over-powered. The hook was at the stern, so I could not find a fix. To fix the other one I just put on a smaller motor (just under the capacity spec) and all was well.

Since your hook is far forward, maybe you have a prayer. Just trim the motor up as high as you can without causing porpoising. You should have no more than 5' of hull in the water when on plane.

What's telling you he has a hook far forward? I can't discern a problem from his pics except maybe post 10. In 10 it's out of focus but if you look at the stern right ahead of the trailer tie down I see what could possible be a hook but hard to tell.

 

[JimS123]

Rated for a 125 and you having a 90 kinda' puts you on the edge of being slightly underpowered. She might just be kinda' "slushy."

A 90 on a 125 is no where near UNDER powered. You won't be the fastest boat on the lake, but with the right prop that boat should run circles.

Look at the pics. Its not a really big boat and its a tinny besides. IMHO putting a 125 on it would make it squirrely.

My fishing boat is bigger, and it runs awesome with a 60 CT.

 

[sms986]

Yeah, I'm more than happy with the speed. It's a little too fast I think, I'll have to get used to it. I'm just concerned with the safety of plowing at high speeds..