Remove from trailer in my yard...

[gsfaulk]

This may sound far fetched (I've seen pictures with smaller boats), but I would like to lower the bow with the crank on the trailer, build a stand under the stern (4 x 4 post and 2 x 4 rails), raise the bow high enough (it has to go up about 8 inches for the uprights to clear and may have to use additional jack) to build a stand out of 6 x 6 post and crosspiece 10' wide, enough to pull the trailer out. I will also have side braces out of 4 x 4 posts and 2 x 4 rails. As best I can figure, the full weight will not be on the front stand until I lower the front of the trailer. I will not be able to get shoring under the keel until the trailer is out. So, in addition to pros, cons, tips and/or advice, my question is, will the 10' span of the 6 x 6 hold the weight of the 1981 27' Hunter until I can get the shoring under the keel? Am I crazy for even considering this?

I added a couple of pictures that I found. Would have side braces in addition...

 

[nola2172]

I will be working on doing this for my boat as well. I am not familiar with how much your boat weighs (for my sample math I used some online info that said 7000 lbs and I rounded 3500 up to 5000 for a bit of safety on each end), but there are some calculators online that show you how much flex you will get (and thus give you a good idea of how well things will hold).

First, here are some numbers you will need for the Modulus of Elasticity of a few different things:
Steel: 29,000,000 psi
Oak: 1,600,000 psi
Pine: 1,300,000 psi

Next, you can go here to figure out the Moment of Inertia:
http://www.engineersedge.com/calculators.htm
-Go to the section "Section Properties Selected Shapes" and pick the one that represents the shape you have. For a 6x6 (which is really 5.5"x5.5", you want "Rectangle at Center." For 5.5 inches square, I got 76.22 as the moment of inertia.

-Next, from the calculators page, go to the "Structural Deflections and Stress Menu" section and pick which loading you want. For purposes of testing, I used the "Beam Bending Equations / Calculation Supported on Both Ends Single Load at Center."

-For this calculation, put in whatever values you need (I used 1,300,000 for E, 76.22 for I, 5000 for W, 60" for x, and 120" for length (l) - c does not matter a lot). This gave me a deflection of 1.82, or almost 2 inches. I know if that were me, I would not want that kind of flex because things might break.

I will add that when I will be putting together my own rig (H240), I am planning to use 2x4x1/4 wall steel beams so that I make real certain that I don't have problems. For your example, these would flex a little over an inch, which still seems like a fair bit to me, so you might need something pretty serious in order to get this done.

 

[nola2172]

Also - in order to get support under the keel are you planning to jack up the boat so that you can get something under it? That seems like it could be a bit tricky.

 

[gsfaulk]

Nola, excellent link! Thanks! I did the calculations with 7000 lbs and got 2.54" deflection...not good. However, and this is just me thinking, this calculation seems to me to represent if you had the 6 x 6 out there and just sat the keel (full weight of the boat) in the center of the beam, you would get the full 2.54" of deflection. A portion of the weight should be distributed to the rear brace which will be in place first and not sure how you would calculate or guesstimate the actual portion of the 7000 that would be on the front beam. Also, at the height I have to get it for the trailer uprights to clear, I can get diagonal bracing in that will reduce my calculated length to 8' thus reducing my deflection to 1.30" (maybe less with some weight sitting on rear brace). That is still a lot, but I only need it to hold long enough to get the trailer out and chock up the keel which will take even more if not all the weight off of the beam. I suppose that kind of answered your question about the keel too, but the problem is that the board on my trailer that the keel sits on runs all the way to the back of the trailer frame so I can't get anything under it until the trailer clears.

 

[nola2172]

No problem on the link - it is pretty handy for lots of things. The reason I used 5000 is that of the 7000 pounds, I was sure that some would be on each end, but I was not sure how evenly it would be distributed so I rounded up. I agree that once the keel is under it you should probably be pretty OK since that is designed to hold most of the weight.

One other thing you mention is diagonal bracing to reduce the length to 8'. In doing this, if you plan on something that does not have direct vertical supports, I would be concerned about the pressure pushing outward on the supports causing them to slip, so you will want to keep that in mind.

I know it will cost a few bucks, but I am guessing somebody near you sells steel beams. Even if they flex a little bit (you can do the math for them on the website as well but make sure to use the rectangular tube section to get the moment of inertia), I would be reasonably confident that they won't break. I was planning to use a steel beam as the primary support and just "wrap" it in wood so that I can connect the wood to other things. That way the steel beam bears the weight but I can use normal wood connections for everything else.

Either way, even though you won't need a long time to deal with the keel, somebody is going to have to be under the boat to do that and I would want to be really certain the boat was not going to fall on me.

 

[gsfaulk]

Duh on my part...I see where you got the 5000 now (1/2 the weight rounded up)...I was thinking that the 5000 was the weight of your boat. Also, agree with outward force concern and slippage. I'm considering putting the posts in concrete for that reason, but really didn't want this thing that permanent in my yard. I'm only planning on doing this once...same concern with steel beam...and I can reuse wood on other projects, not much use for steel beam after this. Thank you so much for your suggestions and input! If I do this, and I know I will, I will take plenty of pictures...hopefully one of them won't be my boat laying over on a crushed pile of lumber and me having to hire a crane (that my wife said I should do in the first place) to lift it back onto the trailer. Fingers crossed!

 

[Rick Webb]

Couple of Questions

I've thought of doing the same thing with my boat though it is much lighter.

First thought why not use three ore even four 2X6s rather than a 6X6 seems that would be much stronger and accommodate any flaws in the timber to prevent anything catastrophic from occurring.

Second in the pictures it appears that the braces were assembled using screws rather than nails. Watching Tommy on "This Old House" he admonishes viewers frequently that screws especially drywall screws are much more brittle than nails and not to use them for these type of applications. Just something to keep in mind.

I have also seen frames built over head and the boat lifted with a couple of "come alongs" also. The frame could then be made into a carport or pole barn I've considered that as well.

 

[gsfaulk]

The overhead frame and shed later was a thought as well, but don't need the expense of 4 - 20' 6 x 6's right now. Not sure if 4 - 2 x 6's would be stronger but it sounds logical, and about the wood flaws too, because my luck the one 6 x 6 that I buy would have an unseen hairline flaw or something. And yes, I will be using nails and lag bolts for sure.

 

[nola2172]

As a note, and you can see this in the calculator, the vertical strength distance is the key one to consider. So, you might want to buy two 2x10's and put them together (so you have 3.5 inches wide by 9.5 inches tall) rather than a 6x6. This gives you a moment of inertia of 214 as opposed to the original 76, so that would be a lot stronger. Even two 2x8s would be stronger than a single 6x6, and I don't remember wood prices exactly, but I think the 2 x whatever is a lot cheaper than a 6x6 and probably more useful for something else later.

 

[Nelsonhow]

Guys,
Been reading all your posts and in MHO ( my humble opinion )you're making a mountain out of a mole hill. Go look in any boat yard and see how it's done. 4 then mid height jack stands and 1 front v stand or six request jack stands work fine to support the board. With six or eight you can jack and reposition to remove a trailer. When you're all done just make sure the keel is sitting a wood 2x6 on op of cement blocks an that the stands are chained together to prevent them. from moving.

 

[Rick Webb]

Another Thought

Man handling a 10' 6X6 would be tougher than a single 10' 2X6, 2X8, or even 2X10 a couple of times that alone makes it a more attractive alternative.

 

[gsfaulk]

Now knowing that I can combine pieces to achieve better results and the more numbers that I have crunched through those formulas, I think I will use 4 - 2 x 8's which gives me 190.46 (I). Using the full 7000 and 120" span gives a 1.02 deflection and using 5000 and 96" span (takes estimating portion of weight and diagonals into account) gives a 0.37 deflection. Hopefully this will work.

 

[gsfaulk]

Hey Rick,
I don't disagree. My two biggest problems are time and money. I need the trailer this weekend to go pick up another boat that I bought for parts. I felt like I could build these braces and use my trailer cheaper than renting a trailer (still having to remove that boat from the rental) and the fuel and time to return it. Also, I'm about 100 miles inland and I'm doing all the work at my house. I still have to paint the bottom before I jump into the expense of a slip in Panama City.

 

[Rick Webb]

Redneck Option

Dig a whole and plant the keel

 

[gsfaulk]

LOL...I think I am doing the redneck option.

 

[Rick Webb]

Been Wondering

Thinking more about the frame and pole barn approach.

Rather than dimensional lumber for the uprights how about poles? What do they go for?

Second what happens to old telephone poles? it seem that a guy could cut out the middle "good" 20 or 25 feet and would work just fine for what we are discussing

Am I delusional thinking this would work?

 

[Nereussailor]

Sandwiching plywood between the 2x6's strengthens them without the weight.

 

[J Hunter]

So how are you getting your parts boat back off the trailer? Another drive out custom cradle?

 

[Gene Neill]

Sandwiching plywood between the 2x6's strengthens them without the weight.

I can vouch for that. Load bearing beams in home construction are at least sometimes built this way.