hey thanks for all the info...very informative..its amazing that those brackets can support all that weight of the boat..How did you take the measurements? Im assuming the measurements have to be precise to make sure the boat sits securely in the bunks..so mfg long and ez loader are two of the best? Should I exclusively be searching for one of these? Are they much better than the rest? So you got all those extension bars that hold the bunks higher from the trailer company? What does a new powerboat trailer of this size go for? sorry for all the scattered questions but you seem to be a wealth of good information..this project may actually be doable after all..Fortunately I have a good amount of time to get this done..I would like to have a trailer setup by october..then I could store the boat in my backyard and not have to spend money on winter storage fees..
My trailer originally had 8" extension brackets and the dealer at Walmsley Marine had the 24" extension brackets in stock and told me that they would work for my boat. A lot of the boat's weight is going to be sitting on that keel board on the cross members. The bunks just keep the boat from tipping over. If you have any reservations or worries about the bunks slipping down, and this is quite understandable, you could cut some short pieces of 2x4s to fit between the bottom of each bunk and the top of the cross members, and zip tie them to each extension bracket. There's no way that they would slip.
When I bought my new trailer, my boat was already in the water at the club and I needed to get the trailer adjusted to fit it. I brought my bathroom scale, tape measure, two of my sailboat stands, and my hydraulic jack with me. I had my truck jack with me also. The first thing I did was set my bunks up to an approximate height which in this case, a little higher is better than too low. I didn't want to pull my boat out of the water leaning over to one side because the bunks were set too low. As it turned out, my keel was off the trailer's keel board about two inches when I pulled the boat out and that was good. I pulled the boat and trailer up on level ground and uncoupled the trailer from the truck and set the tongue on a block with the scale under it. The trailer needs to be level when you get the tongue weight. I needed to get about 210 lbs on the tongue and I was getting about 300 which is too heavy. So I backed the trailer down the ramp and let the boat float back a few inches and brought it back up and repeated the process. I got 211 lbs. Close enough. The next think that I did was put two of my sailboat stands on each side of the stern of my boat, and I took my hydraulic jack and put it under the bow of the boat close to the front of the keel, and jacked it up snug with a block and piece of carpet in between the jack pad so I wouldn't mar the hull. I then loosened all the extension brackets and used the sailboat stands and the hydraulic jack to lower the boat so that the weight of the boat and keel is sitting on the trailer's keel board. Then I placed my two jacks under the middle extension bracket on both sides of the trailer and jacked it up so that the bunks were up against the bottom of the hull and even. This is where the measuring tape comes in. I tightened up each of the two adjusters adjusters and did the same thing with the other four adjusters. The bunk boards will bend to conform to the shape of the hull. The last thing I had to do was move the winch stanchion up into place so that the bow roller is up against the bow of the boat and tighten it down. It took me longer to write this out than it took to adjust my trailer that day. In fact, I was able to put my boat back in the water before the tide went out and bring my new trailer home. I like my Long Mfg Trailer, but it's Aluminum and it may not be suitable for the weight of an O'Day 25, I don't really know. EZ-Loaders are great trailers but I can't say enough about the quality and construction of Long's extension brackets. They're the best I've seen yet. Talk to a dealer first and ask a lot of questions. They could probably set the trailer up for your boat. You really should consider the safety issue of doing something like this. There's a lot of weight involved with these boats. Have someone help you out who is familiar with this if you decide to go this route. You have plenty of time to think about it. Good luck!
Joe