Are trailer bunk brackets always needed?

[Ernest T. Bass]

The bottom of my boat currently sits 4.5" above the top of trailer frame. Does this height seem normal to you guys? I would like to get the boat to sit lower if possible. I am thinking of buying the Ultimate bunk boards for my trailer, and was wondering if I could lay them flat and bolt them right to the trailer frame(without using a bunk bracket). Is this a bad idea? Do I have to use bunk brackets? Thanks.

 

[DrNip]

As long as your boat rides on the bunks I don't see a problem with it. How are you going to secure the bunks to the frame?

I just purchased a set of 6' Ultimate Bunk Boards and they seem to droop more than my previous wooden bunk boards, FYI. I solved this by mounting them vertically. Of course this might be a different story with a boat on them. I am still waiting on my boat so just the trailer sitting in the garage with nothing on the bunk boards over a couple of weeks made them have a slight droop.

 

[marshman]

i prefer my boat to sit as low as possible for launching shallow....i have a few primitive launches i use and it helps alot...

i havent deciding how im doing my bunk on this new trailer yet but i have done flat many times...

just dont forget to countersink the bolt heads....


couple things to keep in mind...

bunks being flat==more surface area....be sure they are spaced to sit between the ribs on the boat bottom...

if your boat has a vee, theres a chance of rubbing the cross brace when loading unloading... normal rollers will stick up too high once you flip the bunks flat.....

 

[Ernest T. Bass]

DrNip » 03 Aug 2013, 19:04[/url]"]As long as your boat rides on the bunks I don't see a problem with it. How are you going to secure the bunks to the frame?

I'm thinking of laying the boards flat on the trailer frame, drilling thru the top of trailer frame, and using bolts and locknuts. If I do this, I would use a 2X4 under the Ultimate boards to increase the strength and eliminate flexing/bowing. That should also lower my boat 1.5"

I never thought of the roller. I'll have to see how high it sticks up now. I only have 1 roller near the center of trailer.

If I bolt a 2X4 to my galvanized trailer, is treated wood OK to use?

 

[Attwanl]

I took the brackets off and laid the 2x4's flat, and put one down the middle, I've got a flat bottom jon. Like marshman said, I just made sure they were between the ribs. It lowered the boat over 4" and seems to be more solid on the trailer.

 

[Ernest T. Bass]

Attwanl » 03 Aug 2013, 21:29[/url]"]I took the brackets off and laid the 2x4's flat, and put one down the middle, I've got a flat bottom jon. Like marshman said, I just made sure they were between the ribs. It lowered the boat over 4" and seems to be more solid on the trailer.

Did you bolt thru the wood and trailer frame? Or did you use some sort of metal angle bracket?

 

[Attwanl]

I used small carriage bolts and counter sunk them in the wood. Don't need to be very big pressure is pushing down, boat should easy and not drag, which is the only thing that would put pressure on the bolts.
Forgot to mention... A 2x4 is it's weakest laying on it side... My trailer had a center support so it did not matter. My little boat doesn't wiegh much, but the 6 gal gas, fishing gear and oh yea....cooler, bouncing down the road.

 

[JMichael]

Attwanl » Yesterday, 20:29[/url]"]I took the brackets off and laid the 2x4's flat, and put one down the middle, I've got a flat bottom jon. Like marshman said, I just made sure they were between the ribs. It lowered the boat over 4" and seems to be more solid on the trailer.

I did the same thing with my trailer and my brothers trailer, except I didn't install a middle runner. For attaching the runners, I welded steel tabs to the trailers cross members at each location that I wanted to bolt the runners down. Then I drilled a hole in the tab to install the bolts through. This whole thing with the tabs wasn't absolutely necessary but it did make installing the nuts/washers on the bottom side of the carriage bolts a lot easier then trying to do it up inside the frames cross members and it didn't weaken the cross members from having holes drilled in them. The tabs look something like this.

 

[sawmill]

I have a trail master trailer and the bunks on it are mounted to the frame of the trailer. It has wide rollers down the middle to hit the center of the boat. On there website now it shows a bracket but mine does not have it. I had a shore line trailer with a starcraft boat before and with the new boat which is a Lund and a bigger boat I can launch in real shallow water. My roller are non adjustable and set about a 1/4 inch above the frame. With the 60 HP Merc if I did not use the motor support I could not haul it on the road not because the motor would hit. Check out their web site to get some ideas

 

[Ernest T. Bass]

Thanks guys. When using the Ultimate bunk boards, do the edges have to be rounded over? Or are they good to go as is?

 

[Colbyt]

Ernest T. Bass » Yesterday, 19:00[/url]"]The bottom of my boat currently sits 4.5" above the top of trailer frame. Does this height seem normal to you guys? I would like to get the boat to sit lower if possible. I am thinking of buying the Ultimate bunk boards for my trailer, and was wondering if I could lay them flat and bolt them right to the trailer frame(without using a bunk bracket). Is this a bad idea? Do I have to use bunk brackets? Thanks.

There is no "one size fits all" answer. It depends on how far apart your cross members are and how much your boat weights. I would have to look it you to be sure but an unloaded 2x4 probably can not exceed 48" CC when laid flat.

 

[Ernest T. Bass]

Colbyt » 04 Aug 2013, 17:40[/url]"]

Ernest T. Bass » Yesterday, 19:00[/url]"]The bottom of my boat currently sits 4.5" above the top of trailer frame. Does this height seem normal to you guys? I would like to get the boat to sit lower if possible. I am thinking of buying the Ultimate bunk boards for my trailer, and was wondering if I could lay them flat and bolt them right to the trailer frame(without using a bunk bracket). Is this a bad idea? Do I have to use bunk brackets? Thanks.

There is no "one size fits all" answer. It depends on how far apart your cross members are and how much your boat weights. I would have to look it you to be sure but an unloaded 2x4 probably can not exceed 48" CC when laid flat.

Thanks. I could use a 2X6 under the Ultimate bunk board instead. That would be a little stronger. I need to measure the span, I think it's less than 4' though.

 

[sawmill]

The bunks on mine are 6 inches wide. On the span between the frame of your trailer you have to remember that your boat weight is spread over a larger area. When they test ths breakage on boards they hit it in one small area. With out measuring mine I think my frame members are about 5 foot apart

 

[Ranchero50]

Mine is laying on the frame. I just laid some 8' or 10' pine 2x4's sideways and reused the angle brackets. I did need the first middle trailer roller and used a chunk of UHMW in the center because the bow would rub when loading. I have 1/2" thick UHWM for bunk glides.

 

[Ernest T. Bass]

Thanks guys. The span between the 2 trailer support members is 44". I don't know if I should use 4' or 5' Ultimate bunk boards. If I use 5 footers, the front end would be unsupported for about 12". Even with the 2X6 under it, that is not good, correct? Should I get 4' Ultimate bunk boards so there's no overhang?

 

[Ranchero50]

I'm not sure about your question...

You should have a roller or another glide for the front center strake. I'd get three 4 ' sections and cut one in half and mount it 6-12" in front of the rear slider. If you use 2x4's laid flat you can force the board to follow the curve of the hull. That's how mine ended up. I'll try to take a picture of it if we get to the river this evening.

 

[Ernest T. Bass]

What do you mean by "rear slider"?

My hull is flat where the boards will go.

 

[Ranchero50]

Sorry, rear set of bunk sliders.

 

[Ernest T. Bass]

Thanks Ranchero50.

Joe from Ultimate Bunk Boards told me the maximum span for the 2X4's is 48", and 60 " for the 2X6's. I just need to decide what size to get.

 

[jackinok]

just a little something to think about,if you pull your boat a whole lot lot on gravel roads its sometimes not a bad thing to have them sitting higher on the trailer. Your truck or tow vehicle will throw alot of rocks with its rear tires,especially with mud grip type tires, and its my belief that a lot of the dents and dings in a aluminum boat is caused by these. Ive actually picked the rocks out of a bass boat on a low slung trailer before. I'm like you in that i like them lower for loading,but my pond hopper thats nearly always on gravel or off road is sitting higher on the trailer. MY opinion of course!LOL