How many bunk boards for 1648 flat bottom?

[redrum]

I bought a 1648 flat bottom and the trailer has four longitudinal bunks under the boat. I thought most jon boat trailers only had two bunks. I ask because the boat doesn't seem to sit properly on the bunks. Should the bunk sit against the floor of the boat or the chines? I've always seen the bunks touching the floor with the chines beside the bunks. There doesn't seem to be enough space for that with this trailer. I've never had a flat bottom before. It seems like it would be hard to get it just right on the trailer without any type of centering roller.

 

[-CN-]

Just two bunks. Centering rollers, one in front and one in back will help. My 14 footer doesn't even touch the center rollers right now so it's just utilizing the two bunks. I made the bunks full length though.

 

[richg99]

My 1648 only has two bunks.

My boat has "strakes" ...i.e. one inch ( or so) protrusions running the length of the boat. I hate those things though I see why they are there ...to support the bottom of the boat. They catch on the wrong side of my bunks. I actually have to lift the boat up and jerk it over to get her centered.

I wonder if your Previous Owner added an extra set of bunks to help with centering???

Today, I am going to make up some stern guide-ons to help. I already made up a centering assist device which works fine....unless I am recovering with a strong side-wind. When the wind or current is sideways, then the guide-ons should help.

richg99

 

[CedarRiverScooter]

I have 4 that extend from transom forward 8 foot, Then the 2 inner ones extend another 8 foot (that provides a great walkway for launching without getting your shoes wet. I just have them spaced so that there is plenty of room for the ribs. I have side guides too, makes loading a cinch (my wife likes to drive it on).

 

[Capt1972]

I have 4 that extend from transom forward 8 foot, Then the 2 inner ones extend another 8 foot (that provides a great walkway for launching without getting your shoes wet. I just have them spaced so that there is plenty of room for the ribs. I have side guides too, makes loading a cinch (my wife likes to drive it on).

Pics?

 

[CedarRiverScooter]

Best I can do for now, hopefully you can see the spacing of the bunks:

 

[onthewater102]

Those ribs running along the underside of the boat are not as well supported as the floor sections and will probably develop stress cracks over time trailering the boat if you have the boat bearing on them while trailered. I'd try & move the bunks a smidge so they sit flush to the floor.

 

[richg99]

No weight bearing on my "strakes" or whatever they are called.

Just took the boat in yesterday to have a trailer manufacturer re-do the bunk supports. They are dropping them and I should be 3 1/2 inches lower on the trailer when they are done. Should help with launch and recover a lot. richg99

 

[onthewater102]

yeah, jons are nice with the flat bottoms that you can run bunks all the way up the trailer and avoid bottoming out on the trailer between the bunks like you can with a V-hull. Lets us launch in skinny water on fishy places the big boys can't get to.

 

[PSG-1]

Mine has 2 bunks:




And they are spaced between the strakes:



After having the bottom of the boat coated with Line X, due to its rubber-like surface, I found that the carpet bunks had way too much 'grab', I had to back the trailer much farther down into the water to launch.

Also, since I use the boat in salt water, carpet isn't a good idea with an aluminum boat, even if the bottom is coated. So, I bought 5/4 composite decking boards, and used a skilsaw to rip the excess off one side so it would be the same width as the 2X4 bunks. Then used stainless steel decking screws, being sure to fully sink the heads below the surface, and then using a hammer to flatten out the hump (that prevents them from backing out) Now it slides like it did before, maybe a little better.

For the ramps I normally use, I can unhook the winch, then attach my 25 ft length of rope to the bow eye with my kicker hook, tying the other end off to the winch stand. When I back in, and hit the right depth, the boat slides off the trailer. Then I slowly pull up until the trailer is far enough up the ramp the boat won't bang into it as it comes to rest on the ramp. Then I step out and unhook the rope from the winch stand, set anchor/tie off, and park the truck.

I wouldn't try unhooking it on a steep ramp, though, as those composite boards are pretty slick. That wouldn't end well.
:shock:

 

[onthewater102]

Good point on the friction - the extra boards are probably going to hinder any effort to power-load the boat.