rtg

I have a distance of about 24" from the rear support of the bunks to the transom. I am trying to determine if I can use 2x6 or need to go with 4x6 lumber. The bunks will have the 6" side supporting the boat. The overall length of the bunks is 10'. The distance between the two supports is about 6.5'. I can not move the boat any more forward because the tongue break away prevents the winch post from going forward.

TIA,

Rob

bamaboy473

As you know, the most weight of your boat sits on the very end of the bunk. I think you've figured out that a 2x6 laying flat has minimal support.

When in doubt, beef it up. I think you're past wondering about it...you're on the right track by looking at 4x6 bunks.

__________________
Rick
Alabama's Gulf Coast
Chaparral 240 Signature (Sold)

xrayengineer

I would go with 4x6 bunks with the 4" side touching the boat. Twe feet of overhand would be no problem. There is a tremendous amount of stress placed on the last few feet of the bunks during trailering. Also, make sure the bunks go at least right to the edge of the transom, or stick out a little bit.

__________________
My boat is a 2008 Sea Hunt 220 Triton with Yamaha 250. Garmin 4212, Furuno FCV-620, GSD 22, Standard Horizon Matrix, XM Weather.

twentynine

What xray said!

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Cape Horn 17, Yamaha F115
with
Elmo the Boat Dog

cheesegrits

Try to find cypress 4x8. Mine are 20 yrs old and still in great shape! If you go smaller than that they will have a tendency to twist with pressure and age. Pressure treated is not what it used to be since they took all the bad stuff out. What they put back into the wood has a chemical reaction with certain metals that actually accelerate corrosion.

rtg

The plan is to cover the bunks with the plastic slide covers. These are 5.5" wide therefore the 4x6 bunks will have the 6" side supporting the boat. The 4" side is not an option with these covers. Also, the supports for the bunks are bolsters with right angle brackets to lag bolt to the bunks. That's the setup.

So I am thinking this should work.....any other thoughts?

TIA,

Rob

xrayengineer

I think that the 4 inch thickness will flex with a two foot overhang and a boat transom and motor at the end. good luck!

__________________
My boat is a 2008 Sea Hunt 220 Triton with Yamaha 250. Garmin 4212, Furuno FCV-620, GSD 22, Standard Horizon Matrix, XM Weather.

rtg

Guess I am surprised no one has asked for the size of the boat and trailer regarding the sizing of the bunks. The boat is a 18.5' Sea Pro DC and the trailer is for a 19' to 21'. The boats weight is roughly 2800lbs loaded. The total load for each bunk is roughly 1400lbs. This is across 10'. Given that 25% in on the last 2' that would be 350lbs. This does not seem extreme on 4x6 PT bunk. Thoughts?

TIA,

Rob

kerno

Another thing that enters into this is where the bunks are with respect to the stringers. If they are directly under the stringers, reaching all the way to the transom is not a critical. Since the stringers should be well tied to the transom, I would not be concerned if the stringers are sitting on the bunks. If the stringers don't match the bunks, take the bunks all the way past the transom by a couple inches.

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Kern O.

rwidman

I'm guessing that the trailer did not come with the boat and you are trying to adapt it.

Something very important that hasn't been mentioned here is tongue weight. You should really get that right before you change anything because that determines where the boat sits on the trailer (or you can relocate the axles).

I'm thinking that if you have a good distance between the last bunk support and the end of the bunks and the boat is resting on those bunks, they will have a hard time supporting the boat without bending. This bend will eventually become permanent.

I would suggest using the largest lumber practical and having the long dimension vertical. Keep an eye on it over time using a straightedge.

__________________
Ron
2000 Camano Troll

HIGH COTTON
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