Boat support stands / trailer transfer

abl1111 · #1 08-14-2008, 11:49 PM

I want to be able to transfer my 23' Tsunami w/ an i/o to and from boat stands and my trailer.

I despise the bottle jack process; set/pump/lift/move trailer back/jack down/move jack/pump/move trailer back/lift...

It's a deterent for me from doing it.

What I want to do:

I want to be able to have my boat on a trailer, place two boat stands under either side of the stern, a bottle jack in the middle - all ready to lift the stern.

then, and here's the part I want a definitive answer for ( if there is one ), I want to put a 10' or so 6x6, or something that can take the weight, in the front part of the boat, w/ each end of the 6x6 on bottle jacks that are sitting on top of cinder blocks, and lift the bow of the boat up and off the trailer.

Then, like a gentleman - roll the damn trailer out from under the boat...

My trailer tires are 8' apart...

What say you ?

RalphNitt · #2 08-15-2008, 08:06 AM

Borrow 4 "YardArm" hydraulic jacks from someone in your area. I utilize them in my sodablasting business. They are really heavy and you'd need a flat tilt deck trailer to move them. If you can't find them, lower your trailer at the nose as far as possible. Block the stern quarters. Get a bottle jack and blocking for the front and move it as many times as necessary to clear your trailer. It's a chore...

Islandtrader · #3 08-15-2008, 10:02 AM

Go to my post.
CSC-Off Trailer

Scroll down on the first page. I do not know if you have a set up that allows what I did...but it was easy for me.

1bayouboy · #4 08-15-2008, 01:15 PM

I hope I can describe this right....
We put the trailer tongue on the ground, got the supports tight under the corners of the hull, then jacked up the tongue and put it on the hitch which lifted the corners off the trailer some. We used two pulleys on chains on either side of the axle and a cable long to hook on the front of the trailer, bacl through one pulley, back up through the bow eye, back throough the second pulley on the other side, then back to an electric winch we chained (it was on a plate). With the truck in neutral, powering the winch pulled the trailer out from under the boat. The multiple loops made the winching slow so you could winch a little and make sure the trailer/truck was moving forward instead of the boat being pushed back. We didn't have to do it, but you can also braced the boat at the stern to keep it from being pushed back.

Frankly I was terrified by the whole process, but a buddy of mine used to deliver and pickup boats in New Jersey and made it look easy. He said with roller trailers he could do some large boats solo. He must have had lots of practice because when I wwent back there with him I saw literally thousands of boats on stands.

1bayouboy · #5 08-15-2008, 01:16 PM

Should have added that sometimes you'd need to use the truck to pull the trailer as you winch....you just have to go slow, watch closely and adjust as needed.

rockdoc · #6 08-16-2008, 08:00 PM

abl1111 , I was thinking of getting a steel beam to do that same thing; don't know if I'd trust a 6" by 6".

rockdoc

Fr. Frank · #7 08-18-2008, 06:39 PM

Measure the widest point of your trailer, make your two front beam supports 6" wider. I use 3 2"x6"X10' PT boards, fastened and glued together. They are stronger than a single 6"x6". I've done it this way for years.

I drop the nose of the trailer down, block the transom corners, raise the trailer back up to level, then pick up the nose of the boat with a 2 ton shop hoist and block it just about 2" higher than the trailer. I pull my trailer out by hand, and then place a support under the center of the beam under the bow.

A regular small 2T shop crane won't work, BTW, as it won't reach high enough. In that case, use a 4T bottle jack.

abl1111 · #8 08-19-2008, 09:11 AM

What size boat do you have FR Frank ? 20 or 23' ? That's an important distinction.

You use (3) 2x6 glued and bolted together - I assume you place this w/ the 2x6' pieces in a vertical position, as opposed to flat ?

As for the lifting, I was thinking of doing this w/ (2) bottle jacks, each lifted a little at a time until the boat was off the trailer. Then slide the trailer out. Seems like it would work, do you agree ?

ScottM · #9 08-20-2008, 01:02 PM

Quote:

What size boat do you have FR Frank ? 20 or 23' ? That's an important distinction.

Look at both his avatar and signature.

Trey1096 · #10 08-21-2008, 04:20 PM

Let me preface this by saying that I’m a structural engineer.

In order to get the beam high enough, you’d have to stack the blocks pretty high. If the blocks you’re using are normal CMU, they wouldn’t have any problem supporting the axial load, however, the lateral force resisting capacity would be EXTREMELY low. After you got the boat picked up, it wouldn’t take much to push it over. This could be a puff of wind, an inadvertent nudge, or maybe just some eccentricity in how they were stacked.

I’m not sure how much weight you’d be lifting in the front, but by code, a SYP #2 6x6 beam with an unbraced 10’ span can’t support more than a 750lb concentrated load at midspan. Fr. Frank is correct in regards to the (3)2x6x10’ beam being able to support more load than the 6x6x10’ (I’m assuming he’s talking about loading the beam in the strong axis, or upright). The code allowable for a (3)2x6x10’ SYP #2 beam is a 1050lb concentrated load at midspan. (Disclaimer: These values are just for a comparison. A lot of other stuff can come into play so don’t go hang 750lbs off a 6x6 and then let your wife crawl around under it. Evaluate the whole system to make sure it’s safe. Allowables per IBC 06, NDS 05)

The chain setup IslandTrader used put a lot of load on the chain supporting the hoist. The greater the angle in the “v” above the hoist, the more the tension on the chain is multiplied. The load through the chain is:

Tension in Chain = Lifted Load/(2*cos(v/2))
Where v is the angle in the chain above the hoist.

In his pic it looks like the angle is about 170deg or so. If the bow of the boat weighs 500#, the tension load on the chain would be 2868lbs. I don’t think it would be hard to find a chain to take that much load, but you’d need to be sure it was anchored off pretty good at each end.

Shrimpin’s method looks pretty good. If the posts are buried deep enough, the dirt will support the posts laterally in both horizontal planes. The beam looks heavy enough to carry a pretty good load, and the steel straps will keep it centered on the posts. You couldn’t figure out the capacity with a lot more information (post embedment depth, soil type, post size & species, beam size and species), but it looks like a good idea.

I say all of this because I’ve seen a lot of people get hurt by focusing too much on 1. components and 2. vertical loads. Not only does each component have to be able to support the imposed loads, the whole system has to be assembled in a manner that will transfer and ultimately resist the vertical AND horizontal loads.

Dry stacking 8” or 12” CMU to 7’ high and then placing a 6x6 across it to pick up the bow of a boat is not safe in my opinion. Even if 100 people have done it and never had a hitch, there is an inherent instability in the system that will jump up and bite someone eventually. Don’t let it be you.

If you have any questions, I’ll be happy to help in any way I can.

Trey