putting a log loader on a barge

Typical job descriptions would be like these:
gathering up logs and tree branches that have flushed down the mtn streams and into the lake and stockpiling them They start up lake and float their way down (the lake is 55 milels long).

Or, taking stockpiled wood and placing it on shoreline for erosion control

Or, lifting log booms sectiosn for repair.

A winch, while a solution to the stability issue, really limits my usefullness. But, if that's my reality I'll have to start working in that direction. First, I want to explore the knuckleboom loader to it's end. Of course, a really small boom loader would work, so the issue is how big can I get and how much can I lift. Another approach, seems to me, would be limiting my boom to picking only in line with the bow and not over the side.

I appreciate all these ideas and comments.
~martin

 

Ok, this one might be tricky, but who knows...
It appears to me that your hull is made of two separate floats which have been connected to make one single hull. How about separating those floats and creating a catamaran barge?

I'm including stability calcs made with the attached Free!ship model (modified for a catamaran configuration), from which you can see that, at 10° heel, GZ goes from 0.24 meters (very close to Ad Hoc's manual calculation!) when hulls are attached, to 1.4 meters when separated by a 1.5 meters gap.
It is a huge gain, means nearly 6 times bigger static moment.

I really don't have time to do more calcs now nor to verify if it can allow you to use a current loader, but I would love to hear Ad hoc's opinion about this possibility. I believe he is the most competent and trained person which has partecipated to this discussion so far, so I'm in listening mode now.

EDIT (PLEASE READ):
SORRY FOLKS, FREESHIP IS NOT REASONING THE SAME WAY MY BRAIN DOES, AND VICEVERSA, PLUS I'M WORKIN WITH DEVIL'S HURRY TO FINISH ALL THE JOBS IN THESE DAYS. SO, THERE HAS BEEN AN IMPORTANT ERROR IN THE FOLLWING RESULTS.
WHAT I HAVE CALLED HERE "HULL SEPARATION" IS, IN REALITY, THE OFFSET FROM THE CENTRELINE. SO, WHERE YOU READ "HULL SEPARATION = 1.5m" MEANS "HULL OFFSET FROM THE CENTRELINE = 1.5 m".

SO PLEASE CONSIDER AS VALID ONLY RESULTS AT THE PAGE 3 OF THIS DISCUSSION. AND PLEASE VERIFY THEM BEFORE PROCEEDING FURTHER.

 

Due to the fact that these are actually 4 hull segments, bolted together, that sounds feasible.
We will have to wait for Ad Hoc´s reply, he´s sleepimg now. (Japan).

 

Just a couple of suggestions from a non-engineer...

1) It looks like these calculations were done with the assumption that the crane was located on the centerline. While it would reduce your reach what would be the effect of having the crane lift from the far side of the boat?

2) Deployable amas... They will also reduce reach but should increase stability a lot.

 

I think everyone is doing a nice job whether i contribute or not, but thanks anyway. Nice to see another independent verification of my rough hand calc's...it is all rough, so all we can do. (gives confidence in the solution and assumptions). However, many good guesses combined are better than one highly accurate answer.

As noted if, and it is an if for now, the hull is made of 2 parts and can be separated, this is the solution. (I couldn't tell for sure form the build picture if this is the case).

So, the first question is:
1) Can this be done, separate the hull into 2 parts?
if so then
2) Is there any operational max beam restrictions?
3) Is there any max beam restrictions based upon cost, function? (ie practical side)

If not, then we can assume this premise and solve this dilemma for martinf.

Capt.
If the crane is simply moved from CL to side, then the rise in VCG remains, but, the TCG increases significantly, ie the vessel starts with an angle of list. This reduces the stability further and could be very dangerous.

 

The 4 hull sections (2 front and two back) bolt together so
it is possible to split this boat into two side by side sections, though it would take some steel and figuring of the reinforcing strategy to do it. And I can definately see how that would immediately improve my stability.

Max beam would be restricted only by highway transport issues. It's already oversized here in Washington when it goes over 12'6", so a nother couple of feet doesn't change things much...it's a headache in any event and always an adventure lifting with my crane, hauling with my trucks etc.

Before I settle on the let's-make-it-wider plan, could we discuss a bit more the idea of lowering the boom vertical mast height? I've attached 2 pictures of the log loader that I've been hoping to use on the boat. I've determined that it will be possible to lower the mast height to 3 feet.

Ad hoc, could I push your generosity even more by asking you to perform the same calcs you did when we had the mast as 10 feet but now with the 3 ft value? I've also redrawn the initial sketches with the new lower mast height.

I am really interested in seeing how this changes things with all else being equal.

By the way, indeed, you all are doing a nice job of helping me work this through. And please, rest assured, this is not idle dreaming going on: I am working very hard at finishing this boat and, one way or another, it will get out there in the water working.
thanks,
~martin

 

mertinf

ok, I've just lowered the height of the crane and calculated the same, for a direct comparison for you.

As you can see the changes are:
13.5 degrees original crane height and now is 10.9 degrees, at 1 tonne lift
and
25.4 degrees original crane height and is now 20.6 degrees.

So, not much chnage and more importantly, the area under the GZ curve has hardly changed. So, still not good and not recommended.

As for the hulls...keep it as 2 separate hulls, not 4. Ive done 4 hulls before, crazy!
Just 2 simple box beams to join, it is not tricky at all.

 

Sigh,
Okay, I guess that settles that. Thanks for running those numbers again.
And, yes, I'll be only splitting it as two hulls, not four--front and back sections simply just bolt right together with no space between.
And, you're right, not so tricky creating space between the two hulls with beams.

So, here's the next question: how much space should I create between the hulls? Daiquiri calculated it with a 1.5 meter gap and showed a 6-fold increase in stability. What do you think?
By the way, would you tell me here or pm me your full name so that I can add you to my list of helpers on my blog www.seamule.blogspot.com?
You, too, Daiquiri!
thanks again,
~martin
p.s. I'll be away from internet for 3 days starting tomorrow am

 

martinf

Okay, I think the issue now is, what is, if any, practical limitations are there to the separation width? Point No.3 in post #20.

 

Oh, one final point. Better check with the harbour master or whom ever is in charge, what regulations, if any, exist for such boats. There must be some somewhere for this type of operation on your waterways...

Oh..and what is the maximum lifting capacity you want?

 

I have the steel, the welding skills, the low boy and Mack truck to haul the finished boat.

The issues related to attachment design, necessary beam strength etc are more familiar ground for me (though I am sure open to any ideas/advice in this, too)

I'd just love it if you or whomever could give me the your estimate of the number: how much distance shall I separate the two hulls in order to have a fairly good margin of stability for a side lift of, say 2 ton (might as well think big, huh?!) That's getting close to the max lift of the loader and most likely the max weight of most logs I'd be moving around
The boom mast height, since it doesn't affect the stability all that much can be, can that stay as original of 10 or should I cut it down? 5' or 3'?
Here's a picture of the front two hull sections as they are now unbolted and waiting for sandblasting and painting (macropoxy 646) and a fixed up Sea mule with a front only winch (though exactly how this thing works and what they use it for I've not been able to ascertain) and finally one of the back sections being transported up my road in the back of a dump truck. Um, don't ask.
~martin

 

"...I'd just love it if you or whomever could give me the your estimate of the number:.."

That is the easy part actually. But in order to ensure you have the correct separation and safely and for up to 2 tonnes, and for many years usage etc, we need the answers to those questions. As with most things, less haste less waste. It is sequential.

If you can't get answers to the Qs, then we could use some "international" standards and our best guesses, from previous experince/vessels.

Middle pic looks very nice...something to aim for perhaps??

 

By Questions, I am assuming you mean in your post #20?
1) Can this be done, separate the hull into 2 parts?
if so then
2) Is there any operational max beam restrictions?
3) Is there any max beam restrictions based upon cost, function? (ie practical side)

I'll take a whack at answering these, though I may need you to clarify because I might not be giving you what you are asking for....
1- Yes, definately.
2 - By restrictions, do you mean imposed by governing bodies? Is pretty loosey goosey here and there are two other barges on the lake, both of which are much wider than mine would ever be, say 30 feet.
3 - Cost, well, it's my sweat, so just the materials won't be prohibitive since I'd use box beam most likely. Function, well, getting it from my shop to the lake won't be easy whether it's 13.5 wide (now) or 16 wide. They're both oversize, but I'm only 3 miles from the lake. Mooring won't be any different issue. Turning I doubt will be drastically altered--slow boat, big props and can turn almost on its axis.

Bottomline here is that assuming structural soundness of sperating box beams, I think that we could make the separation distance most anything we wish...well, within reason. I don't think I'd want to go over, say, 2 meters and would prefer to stay within 1 meter as that would be pretty easy to accomplish structurally. BTW, the front hull sections are already seperated by 1" and the back sections by 12". The water cooling radiators for each engine are in this middle area. Front to back sectionline are tight bulhead to bulkhead.

I'll be able to check in in the morning before I'm out for three days backpacking with my daughter in the mtns in which this lovely lake is located. it's quite a special lake: 1500 ft deep, 55 miles long, 3/4 shore line nat park and water quality so good you can drink right out of the lake anywhere you wish.

~martin

 

Martinf

Ok, those replies answer my questions.

So, since daiquiri's calc's for initial hull were very close to mine, i'll use his hull separation GZ's, to provide a solution. Since no point me redoing what has already been done.

See attached. using the 1.5m hull separation, and accounting for box beams, approx 1tonne each, and maintaining the same height of crane, not the lower version.

This will give you around 4 degrees, maybe 5degrees at 2tonne lift....with the outreach you ahve. Should you accidentally on purpose overload her, to 3 tonne...the list is greater but not serious and the reserves of GZ area is more than adequate.

At some 4~5degrees list when lifting the 2 tonne, doesn't sound much, but you will sure feel it. Having the lower list angle also means less lose gear moving about on deck and when a vessels passes, the wash wont make you jump overboard fearing for your life too.

The 1.5m also allows for much better maintenance, easy to get between for cleaning painting, removal of debris etc.

Cheers daiquiri...saved me re-calculating lots of iterations

 

May I raise a point concerning the crane itself; standard truck-mounted cranes often have a slewing (not shure it's the right word, "rotating mechanism") unit that does not stand the forces when swinging a load while heeling! A few years ago I built a selfpropelled barge, 15 x 6 m for a similar duty. The Norsk Veritas people accepted a maximum heeling of 5 degrees with a crane where the swinging mechanism was taken from a bigger model of crane.

One way around your rather low side-stability might be to use retractable legs on the side you use for lifting. And, for your own safety, use the above stab. checks to ascertain whether you can load enough on deck to make a profit!