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Hey guys,
New guy here to the forums for the most part. Usually I just lurk and read everyone else's posts.
So, the good news is I just purchased a place at the lake. I need some help with the boat lift.
I have a 2003 Launch LTS DD.
I have no clue how far apart I need to space the bunks on the lift frame. Should I use 2x6's or 2x8's?
Can anyone help?
You can use either. The spacing depends on which you use . ie the 2x8's can be further apart than the 2x6's. Weight is really not a factor as it is the cross members that support the load. That being said, the wider the boards are apart the less strain on your cross supports, as the point load is further out from the center of the beam. This will give you less flexion on a narrower beam and allow more weight to be carried. While the boat is on the trailer figure out the pick up points according to the lifting beams. Taking a level on the keel measure out to a point of 4.5 to 5 inches for a 2x6 or 6.5 to 7 for a 2x8. This will give you the spacing at the front with .5 to 1 inch clearance from the keel to the beam at the front of the boat. Do the same at the stern keeping in mind that you have to have driveshaft clearance. If you load your boat too far forward be wary of the driveshaft hitting the rear x beam. On a DD the weight is more centered vs a vdrive where the weight is more to the aft so the rear support should be more towards the aft of the boat for a more even front to back weight distribution on the beams. You also want to have the front beam about an inch higher than the back beam to make loading and unloading easier.
On my outback I used 2x6 but when I bought my 21v I went to 2x8 to get a wider spacing on the beams as it is about 1000 lbs heavier.
You also have to take into consideration where the strakes are on the boat. If you are too close to them it is easy to get the boat lifting tilted if its not centered on the beam.
Last year when I had my lift redone I patterned the bunks to what I had on the trailer, spacing etc. My dock guy used a composite wood that didnt need carpet and would not rot. Depending on the roof, boat length, type of lift, try to configure the boat as forward as possible to protect from weather.