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Nose Plowing

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my other ride
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Abandoned boat on canal
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manucanhunt

Member
I have been having a problem with the nose plowing and my boat not planing in deeper water, more than 6 inches. This is deep for where we run the boats. This causes drag, and unless I am in really skinny water, slows the boat and causes the water in front of the boat to actually shoot forward about 4 feet.

I do know that at the very back of my aluminum boat, where the bottom meets the stern, has formed a natural trim as it curls downward about the last 1 inch. I suspect this may tend to raise the rear and possibly cause the nose to plow a bit.

I also just replaced my motor mounts and wondered if the angle of my motor may contribute to this due to the mounts being a bit smaller that the ones replaced.

I have a 16 foot aluminum boat with a Lycoming 0-435. The boat design is a more "traditional" one with a windshield and seats in front. It is run in Utah where we hunt in more extreme conditions. 10 degrees and snowing, at times.

I have been facinated by the number of people who have a vast knowledge of airboats on this forum and would appreciate any suggestions.
 
A cup in the rear will make it plow all day you need to fix that. As for the motor that is like a fine tune knob. You raise the rear of the motor to bring up the nose or lower the rear of the motor to stop a mild propose. However if your hull has a curve in the rear the motor angle cant over come it! The last foot of a hull is the most important when on a plane.
 
Ypou may just need to get some heavy PVC and some friends to fill all those seats and balance the all up boat. The balance point should be about 2/3 of the way back from the nose to the stern.

Lot of different iddeas on how to set the engine angles. I use 1/4 bubble down in the back.

I would think you might consider making the bottom flat and not turn down in the rear. Use a trim tab when it is necessary instead of bending the bottom.

Just some thoughts.

Scotty
 
Thanks!!! I suspected that the cupping in the rear was a problem but it looks like the slightly lower motor mounts on the rear may have accentuated it.

Could I pound the inside back portion to level the cup or would that damage the integrity of the aluminum?

Should I also get a higher motor mount as well or wait until the cupping is corrected before I start playing with the mounts.
 
Airboat munufacturers use "dead blow" sand filled plastic hammers to remove bottom hooks, bulges and dents. Strongly suggest you get your hull bottom as flat as possible before going anywhere else.

Trying to adjust an engine angle to compensate for a bottom "hook" is like bending your scope to make the crosshairs find the bullet hole.

Your boat will never perform properly until the bottom is fairly strait.....

Just wondering, does your trailer properly support the transom or, is that support slightly in front of it? If it's in front of the transom, driving down a rough road will put a perfect hook in your hull.
 
nose plow is 1 inch on the stick from wrecking. it seems that over a period of time esp. on boats over 14ft they develop a hook in the bottom . 1or2 jacks across the stringers and you can tune it to ride the way you like.
 
This is the brilliant quote of the day!

Trying to adjust an engine angle to compensate for a bottom "hook" is like bending your scope to make the crosshairs find the bullet hole.

If you can get a straight edge on your boat it may have a crown going side to side but from front to back it should be flat all the way until the bow curls up. Also 80% of the airboat manufactures don't put in transom supports this is ridiculous because the rear of the hull is the most crucial and they always cup in right before the transom. So your best bet is the dead blow hammer just as suggested. I just changed mine using epoxy to the positive a 1/16 of an inch two to three inches before the transom and my boat porpoised, so I sanded it down a tad and now she runs perfect. The scope analogy was a classic!
 
The transom is well supported by the trailer. When I inspected the bottom, I thought the same thing that the cup had formed by trailering. I'm not sure at this point what the cause was but I will take your advice and get the cup repaired. I wish we had the amount and types of expertise around here, but I'm sure I can find someone who has the skills to repair it.

Thanks to you all for the great help. I always enjoy reading the forum. I can't tell you how much of your advice I utilize!

I did like the scope analogy, as well!
 
Manucan, try to find a metal fabricator in your area ...... somebody that has worked with metal for a few years and really understands it. Don't think that you have to go to a boat dealer. They won't have a clue.

Just from what's been posted I think if you get the cup hammered out of that hull your problems will over. You said that the trailer is straight but that you run a lot in very skinny water. That (pounding from the bottom) is what has probably caused this. You might look at reinforcing the bottom back near the transom for the future, but from the inside so that you don't change the bottom contour.

olf
 
manucanhunt - You can do this. Granger Supply sells the dead blow hammers. One of 2.5 or 5# will do the trick. They also sell dead blow bucks. Or, just get a 4x4, stand it on end and whack away - it will take the hook out. Work from the center line outward.

If there is an inward bulge in the center of your boat, those are best taken out through an adjustable hull jack. A 15' aluminum boat would usually have one in front of the engine and another at the rear of the engine.

Somewhere in the archives here are great pictures of adjustable hull jacks.
 
This is a great thread.

My buddy just discovered a [very] small dent in the center of his hull about 8" from the stern. He says it is making his hull run too much on the nose.

I looked at it and, to be honest, it didn't look like enough to do anything. But, like Thunder said, the last foot is where everything is going on when you're up on plane (or in your case, trying to get on plane)

I wish there was a book about airboat hull design, I'd sure buy a copy
 
adjusting engine angle has very little effect. i know everybody before me has said it, but i'm just reinforcing the idea.
 
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