Trailer bunk adjustment

HawkX66

Well-Known Member
Jul 27, 2020
1,344
SE Virginia and NH
Boat Info
"Tread Knot"
1997 Sea Ray Sundancer 290DA

2020 F350 6.7L
Engines
454 L29 Carb w/ Bravo III
When I bought my trailer it was fitted to a 2006 290DA. My boat is a 97 290DA. It seems to be really close, but the bunks are currently sitting on the OE through hull transducer and the water ports. I'm not worried about the transducer because I don't use it.
My question is whether it's ok to just move the rear of the bunks out a couple inches or should I move them out equally? This would make the bunks a little bit of a V. If outboard isn't enough, how far in is safe?
Here is what it looks like right now.

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If you move the rear bunks out the boat will sit lower on the trailer. If you have enough clearance between the boat and the trailer, I would move all of the bunks out to keep the boat sitting level.
 
If you move the rear bunks out the boat will sit lower on the trailer. If you have enough clearance between the boat and the trailer, I would move all of the bunks out to keep the boat sitting level.
I'd rather go outboard, but I'm not sure if it'll move far enough over and I'm not sure if the keel will have enough clearance to the cross bar. I guess at this point I'll just have to move it and see.
 
You should keep your bunks parallel to the center line of the hull considering you trailer doesn't have a bunk for supporting the center to carry the weight. Any angle would cause the weight of the boat to push sideways on the bunks and will cause the boat to sit not parallel to the trailer and who knows how it would effect loading and unloading . Considering how your trailer is setup to move them outside of the ports would drop the boat down on top of the axles. If you make some taller bunk boards you could move them out . If you have a custom trailer shop in your area take it to them and see what they think. Another possibility would be to install brass ports then if you did slide up on them you wouldn't break them.
 
You should keep your bunks parallel to the center line of the hull considering you trailer doesn't have a bunk for supporting the center to carry the weight. Any angle would cause the weight of the boat to push sideways on the bunks and will cause the boat to sit not parallel to the trailer and who knows how it would effect loading and unloading . Considering how your trailer is setup to move them outside of the ports would drop the boat down on top of the axles. If you make some taller bunk boards you could move them out . If you have a custom trailer shop in your area take it to them and see what they think. Another possibility would be to install brass ports then if you did slide up on them you wouldn't break them.
Thanks. They're already brass. I felt like parallel was the right thing to do. Thanks for confirming. I'm not sure it would come to the point of dropping the keel on the axles if I move outboard. The axles are the same height as the dropped cross bars.

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I have a similar set up, moved rear bunks out evenly (front and back ends) and it worked well. Personally, I would not have it sitting on that brass water inlet, that places an extreme amount of weight in a small area, when towing and the weight of the boat is bouncing, could lead damage. If clearance is an issue, you could switch to taller bunks.
 
I have a similar set up, moved rear bunks out evenly (front and back ends) and it worked well. Personally, I would not have it sitting on that brass water inlet, that places an extreme amount of weight in a small area, when towing and the weight of the boat is bouncing, could lead damage. If clearance is an issue, you could switch to taller bunks.
I agree. I don't want to sit on the inlets. At minimum it can damage the bunks. At worst it could put too much stress on the hull in one spot like you said. I'll go out today and see if I can adjust it without taking the boat off the trailer.
 
The bunks themselves do not have to sit on the crossmembers. They usually have several holes in the angle brackets for raising them. Spreading and raising them may be the way to go. When setting up ours, we set the bunks on bolts in the lowest hole and drilled/bolted the bunks in place in the top ones.
 
The bunks themselves do not have to sit on the crossmembers. They usually have several holes in the angle brackets for raising them. Spreading and raising them may be the way to go. When setting up ours, we set the bunks on bolts in the lowest hole and drilled/bolted the bunks in place in the top ones.
I think there is plenty of adjustment available if it comes to that. I'd like to keep the center of gravity as low as possible though, so hopefully I can just move them outboard without having to adjust the bunk height.

IMG_20210110_112544_1.jpg
 
Going by the pics I think I'd move the bunks out and raise them up to the top bolt hole in the brackets. This maintains about the same clearances and fit of the front centering bunks too.
 
Never had a trailer that didn't have center support to bear the weight and the outer bunks for stability.
I haven't seen a bunk trailer for a boat this large with center supports. Were the trailers you had for your current 310 or one similar in size?
 
I have had a roller in the center for loading on shallow ramps so you didnt hit the cross members but it never touched the keel once loaded...this was up to 26'
 
You could just make a notch in the bunk where the water inlet is. Give yourself an inch or two for leeway. It won't hurt anything and might be easier.
 
I added urethane pads to the axles and crossmembers on my trailer. I had to keep the bunks low and out to stay under 13’ to the radar mount.

I’d go out and stay low and add the pads. No issues whatsoever
 

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