Boat moves side to side on trailer

2017 Alumacraft MV1648 NCS.
2017 Karavan trailer.

With the boat strapped down tight (winch and bow strap, 2 individual transom straps) I can slide it side to side on the trailer.

Surely this can't be right.... none of my other boats moved on the trailer.

Is this just the case of my dealer not setting the bunks up correctly? I'm not sure where to start...


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Pictures would help a lot.

I'll grab some when I get off work here shortly.


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I missed that it is a new boat - I would go back to the dealer for adjustments.

Bow.


Port.


Starboard.





If other pictures would help I'd be glad to take them.


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I also noted in the Alumacraft handbook I got when I bought the boat, it said the bunks were supposed to stick out an inch past the transom. Mine are currently flush. Is that going to cause problems?

*edit*

Picture of handbook.



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I can't tell from your pictures but are your bunk brackets adjustable for angle? If yes, then next time you go to the lake, launch the boat and then adjust the angle of the bunks a little bit so the boat will sit in a slight cradle or V.

You don't say how much it will slide but do you have small wind guides or loading guides on your trailer??

You could adjust your right side bunk out wider so that the bunk is closer to the inside of the outer strake (not sure that is correct term) which should stop the sliding.

As long as the bunk is flush, it probably won't hurt anything, but a simple solution is to move the bunk board itself back a couple inches when you have the boat in the water. It's a 20 minute job, just take all the tools you need with you, launch, make the adjustments and go fishing. Then see how it loads after you caught that big one.

They do adjust for angle.

The boat only moves an inch or two in either direction. It was enough for me to notice though.

I do have loading guides. They're adjusted about 2inches out from the hull when it's centered. I thought about moving them in more...


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Are the bunk brackets moving tilting to the right and left or solidly mounted?

You can tilt them either direction. They appear to be tilted slightly inward.

As for how they're currently adjusted, I can't comment. I will check when I get home.


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I would move the right side bunk out some to where it will be closer to the outside strake. It might make loading a bit harder but you should be able to "bump" the hull to make it sit level once the trailer as the strakes may be on the bunks. Then attach the transom straps.

You can try angling the bunks a bit more too unless the hull is a true flat bottom. Not familiar with your hull.

I usually have to bump my hull to center it up on my trailer before attaching the straps but it is a Alumacraft Classic CS 16 with a 60 hp which is heavier than yours.

The manufacturer of my boat, Klamath, emphasized the need to have the transom sitting solidly on the bunks. Kind of makes sense if you think about it. Can't tell from your photos, but if you have a gap there you may want to adjust the bunks further.

From the photos, it looks like your bunks are not symmetrical. The right side bunk seems to be more inboard than the bunk on the left side (where the transducer is). Might not be the case, but sure looks that way to me. Maybe the same thing TNtroller was talking about. I also agree with TNtroller about moving the right bunk closer to strake. If you do that and move your loading guides in to maybe about 1" clearance, then unless it is windy the boat should want to settle down with the bunks between the strakes.

There is a pretty easy way to fine tune the bunks without having to remove the boat. Lower the tongue jack as far as it will go. That will cause the transom to rise. Put some solid supports from the ground to the underside of your transom. Put these in a place that won't interfere with the bunks (I made a quick and dirty cradle from some old 2x4's). Then raise your tongue jack. The rear of the boat will rise off the trailer. Of course you need to remove transom tie-downs or this isn't going to work very well . I like this method because it allows you to fine tune the bunks to exactly fit your boat.

After a lot of reading and talking to a couple guys, the general consensus seems to be the bunks are mis-adjusted. Since the boat is only 2 weeks old, I'm going to take it back to the dealer and have them do the adjustments.

I shouldn't have to mess with a brand spankin' new boat and trailer bought together as a package. At least, that's my thoughts...


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shooter5635 said:

After a lot of reading and talking to a couple guys, the general consensus seems to be the bunks are mis-adjusted. Since the boat is only 2 weeks old, I'm going to take it back to the dealer and make them do the adjustments.

I shouldn't have to mess with a brand spankin' new boat and trailer bought together as a package. At least, that's my thoughts...


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Heck yeah, I would do the same thing. I missed that it was a brand spanking new boat. I'm sure they will take care of it for you.

shooter5635 said:

I shouldn't have to mess with a brand spankin' new boat and trailer bought together as a package. At least, that's my thoughts...

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That ain't how the real world works, friend...... #-o

Only thing to keep your boat from moving left to right is your tie down straps,, if they are vertical or near vertical and parallel to each other its going to allow the boat to shift sideways at the tailend of the boat,,,, straps need to have a 15 to 20 degree angle on them or more to stop the shifting,,, lets see a pic of the transom tie downs installed ,,,,,,,,,,,your bunks need to be centered of the ribs in the hull, dont want to pull the boat out of the water and have it sitting on the ribs ,,

My north river has a factory custom built trailer matched for the boat and it will shift on the trailer without the tie down on or tight,,, but on my g3 ended up with the straps almost plum vertical and it can shift on the trailer ,,, guess n ill get it modified some day

a suggestion would be to criss-cross the straps and see how that works.

When you take it to the dealer. 1) have them move the winchstand forward enough so your transom is sitting on the bunks. It's a must to keep from getting a hook in the bottom of the boat. 2) have them center the boat on the trailer. With the drain hole at back centered between the outside rails. 3) Go beneath the boat and move bunks out to within 1/2" of the outside hull strait. Then move the mounting brackets out on the cross frame to no more then 30* to the outside. When done measure from gunnels to pavement on rear. If it's the same number your done. If not you can raise the low bunk or drop the high bunk so the boat rides level. Your bunks are way off. That's way the movement.


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gatorglenn said:

When you take it to the dealer. 1) have them move the winchstand forward enough so your transom is sitting on the bunks. It's a must to keep from getting a hook in the bottom of the boat. 2) have them center the boat on the trailer. With the drain hole at back centered between the outside rails. 3) Go beneath the boat and move bunks out to within 1/2" of the outside hull strait. Then move the mounting brackets out on the cross frame to no more then 30* to the outside. When done measure from gunnels to pavement on rear. If it's the same number your done. If not you can raise the low bunk or drop the high bunk so the boat rides level. Your bunks are way off. That's way the movement.


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The dealer wanted me to empty the boat (it's hunting season so all my gear is in it) and pull the motor before they'd touch it, so I did some research on bunk adjustment and did it myself. What you described is basically what I followed. It no longer moves. Thanks!


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[emoji106]


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