1680 Mod V Landau Plowing at WOT

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thebobcat

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Hello guys! Great forum you've got here. Got an issue with a boat I picked up this winter. Its a 2001 Landau 1680 Modified V with 60 Mercury 2 stroke engine. It has side console steering and is rated for max HP of 60. The boat planes easily and cruises nicely however when I apply full throttle the boat will push the bow down and plow into the water. The water is breaking at the front of the boat. When I try to trim the engine up to raise the bow and increase speed and RPM the bow never really raises and the prop will blow out. Also if the engine is not tilted nearly all the way down it will blow out easily in turns. The transom is a 20 in angled transom and the engine is a 20 inch shaft. The engine is mounted as low as it will go. The anti ventilation plate is just even with the bottom of the transom at neutral trim. I raised the engine a couple of holes just to eliminate that as a problem and the condition was not better or worse. The prop hub is not spun so that is not the issue. At WOT and in a plowing condition the boat is running 31 by GPS. The engine feels like it is lugging and has RPMs to spare but all the drag of the hull is holding it back. I have noticed on the bottom of the hull at the transom there is a hook right at the transom across the entire beam. With a straight edge the hook is probably 12 inches long towards the bow and the gap between the straight edge and the hull is maybe an 1/8th of an inch. It almost seams as if it came from the factory because it is very uniform across the transom. I like the boat and the layout and the motor runs great but it is frustrating not to be able to run at high speed if needed. Anybody have any ideas?
 
I don't have a way to physically weigh it but I know the boat weighs 400 lbs from factory.
Engine is spec'd at 250lbs
2 batteries x 50 lbs=100lbs
12 gal of fuel x 6 lbs=72 lbs
Approximately 100 lbs miscellaneous
and my self 270 lbs
Roughly 1200 lbs total

The fuel cell, batteries, and myself are all in the rear of the boat. only thing on the front of the boat is a trolling motor.
 
I was thinking foam below deck might be seriously waterlogged adding a lot of weight.

Even if the engine is not mounted perfectly the boat shouldn't take that attitude.

If there is a waste transfer station nearby you can probably get them to let you weight the boat / trailer on their truck scal for a cold beer. That will at least tell you if you're in the ballpark.........
 
That hook is likely the problem. Could be factory though. The faster the speed the greater the stern lift from the hook.
 
Skiffing said:
I was thinking foam below deck might be seriously waterlogged adding a lot of weight.

Even if the engine is not mounted perfectly the boat shouldn't take that attitude.

If there is a waste transfer station nearby you can probably get them to let you weight the boat / trailer on their truck scal for a cold beer. That will at least tell you if you're in the ballpark.........

Ill try to get it weighed. There is a landfill right around the corner from me. I honestly dont think this is the problem thought as I can easily lift the tounge of the boat trailer and push it around easily by myself. I'll try to do this though to eliminate it as a problem.
 
vahunter said:
That hook is likely the problem. Could be factory though. The faster the speed the greater the stern lift from the hook.

I'll try to get pics today of the hook to see if you guys think it is enough to be causing me this issue. Makes sense thought because at cruise speed it rides nicely. The faster you go the worse it gets. It is definately a hook from the factory. I'm begining to think that this hull just wasn't designed to run at a high speed but the boat is rated for the HP that I have.
 
vahunter said:
Where are your batteries and fuel tank? Could also have to much weight forward.

There is nothing in the front of the boat other than trolling motor. Batteries, fuel, and myself are at the rear.
 
I'm not familiar with landau boats but assuming it has lifting strakes on the bottom. Are they all hooked or just the outer ones? Are they hooked equally? Id try knocking out the hook to 1/16 and running it but depending on your boat setup you may not be able to access the strakes from the inside of the boat.
 
Ok. So I went out this morning to take some pictures of the bottom of the boat. They didn't turn out to well and you couldn't see much so I didn't go through the trouble to post them however the more I looked at it I realized where the hook came from. I guess over the years whoever had this boat never used a transom saver. There is a triangular shaped brace that runs from the transom to the keel of the boat and welded to the first horizontal brace. The weight of the engine on the transom had pulled up on the keel and the first brace causing it to hook all the way across in a uniform manner. I've got the hook knocked out now and the bottom is relatively flat at the transom so we will try this and report back. Will be using a transom saver from here on out.
 
Well guys, I'm glad to report after knocking the hook out this thing ran like a whole new boat. Top speed went from 31 and plowing to 38 and a nice attitude. It really is amazing the difference in how the boat ran. Thanks for everyones help.
 
Sometimes hooks can be caused by trailering , make sure the transom has support under it when its on the trailer otherwise it may hook again ,rollers will hook an aluminum boat, carpeted bunks properly placed will not
 

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