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Boat support on the trailer???

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Old 11-06-2011, 10:58 PM
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Default Boat support on the trailer???

I am rebuilding an aluminum I-Beam trailer and its on an old thread so I am asking questions with a new thread...see the old thread for pics if you are curious to what I am doing.

http://www.offshoreonly.com/forums/t...questions.html

I have raised part of the boat off the trailer to start working on crossmembers and boat support. Just curious how high off the trailer is too high for the boat to launch. Right now the bottom of the transom sits level with the bottom of the I-beam and rises up the farther forward you go. I am wondering if I make straight crossmembers and bring the transom bottom to the top of the I-beam (7 inches) if it will be too high on the trailer.
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Old 11-07-2011, 07:54 AM
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Probably not. I just finished rebuilding a Loadmaster trailer last summer and went with dropped center cross members, but then I added bunk supports that raised the hull back up off the cross members. The end result is that the keel is at or slightly above the level of the top of the cross member. The boat launches fine. One other thing to think about is the angle the boat is carried on the trailer. On the original trailer (Heritage) the boat was carried bow high. When we did the Loadmaster, we set the trailer up so that the boat is carried level (parallel to the frame rails). This did two things for us. One it effectively raises the outdrive and reduces the chances of hitting the drive when loading, unloading and storing the boat. This is a single engine boat with a deep drive. Secondly it makes getting into and out of the boat (at the ramp) easier since the bow is effectively lowered. With this set up, I do have to put the trailer in the water more than we did with the bow high setup. It is not much of a difference however and overall we like it being carried level.

I would be concerned about not having much contact between the boat and trailer if you are just counting on vee blocks as contact and support at the keel/cross member interface. A lot of concentrated loading here.

Good luck.

Dan
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Old 11-07-2011, 12:19 PM
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Did you use aluminum or galvanized drop centers? One thing I am doing is getting away from bolting to the bottom flange. I have seen a lot of threads with the ibeam bottom flange ripping away from the webb. I am either bolting to the webb directly or welding the crossmember to the webb and flanges. I have also seen longer bolts to the top flange with a backing plate. I beams are designed to have the load on the top flange, not the bottom flange.
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Old 11-07-2011, 12:28 PM
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I like having the boat as low as possible on the trailer. It makes for easier loading and launching, especially at shallow/tidal ramps. Not to mention easier to board when on trailer, and lifting things in and out. The only real positive with having the boat higher is it's further away from the tires if you have a blowout. But as long as you have strong fenders and full inner fender coverage, your fender should protect the boat from tire blowouts.
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Old 11-07-2011, 12:37 PM
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Forgot to mention those V-Blocks will be history. I will have forward bunks.

I have steel fenders going back on, the original aluminum fenders were very flimsy. I got a steal on the fenders since they were ordered and not picked up at a local shop. They accidentally left them outside and they rusted. I blasted them then dropped them off and had Bullit Coating applied. I will add an inner protector once they are installed on the trailer.
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Old 11-07-2011, 04:22 PM
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Don't see any benefits by going higher than necessary. Plus might be a hit or miss as far as fitting under a garage door.
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Old 11-07-2011, 04:31 PM
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In hindsight I should have ordered drop axles...my shop plans call for 12 foot doors so thats not an issue. Its the crossmembers and how I attach them to the I-beam that may raise the boat on the trailer.
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Old 11-08-2011, 08:51 AM
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I gotta say I really like my higher trailer, where others have trouble launching I do not.
I never have to worry about or raise the drives.... only issue is for winter storage but if thats not an issue for you then great.
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Old 11-09-2011, 10:18 AM
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Originally Posted by Prater View Post
Did you use aluminum or galvanized drop centers? One thing I am doing is getting away from bolting to the bottom flange. I have seen a lot of threads with the ibeam bottom flange ripping away from the webb. I am either bolting to the webb directly or welding the crossmember to the webb and flanges. I have also seen longer bolts to the top flange with a backing plate. I beams are designed to have the load on the top flange, not the bottom flange.

Good point. I have drop axles and aluminum drop center crossbeams. I am bolted to the bottom flange of the I Beam. Bolts on the outside flange and U bolts on the inside flange. I may take your idea of a longer U bolt to the top of the flange with a backer plate and run with it. I have never seen a failure bolting to the bottom, but I don't want mine to be the first I see either! Good idea.
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Old 11-09-2011, 11:18 AM
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Here is one I remember on the Hull truth. there were a few more simular pictures with smaller boats than ours.

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