Spud for work catamaran/barge deck?

Hello!

We are about to finish last components like cleats, nav lights etc and send her off for power, twin 70hp. She is a almost 300 sq ft foot platform (aluminum deck, supported by C channels all 5052 marine grade with coatings) on two bulkheaded/bow reinforced fiberglass pontoons that can displace about 15,000LB at 18" draft. We work my oyster farm, and need her stationary to bring heavy bags of oysters to her, hoist them up, and sort on our tumbling machine. Two anchors fore and aft seem like a pain and still some swing depending on weather. I am interested in spuds, but have seen very few DIY examples. A contractor working piers in coastal AL (where I am) built one. It seems like a large pipe fitted to a bracket on the side of the boat extending over the deck for the sleeve, heavy steel bar and a winch to raise it. Cant find or track down pictures. I have access to a local fabricator, but I am worried about stress to hull and deck. It wouldnt sit over night or in heavy weather, just for calmer days when we need her in the same spot. It could be fairly light I suspect, with a bow anchor holding the boat into the weather and the spud just stopping swing. We have small 1-1.5' tides here once a day so you can anchor reliably, just have swing and we work short handed so cant reset anchor every time wind shifts if 100 yards away on the farm. Maybe just standard anchors?

 

Shallow water pole anchors are relatively simple. It should not be too difficult to design.

There are a few diy versions that are under engineered for your needs, so you start off by understanding the requirements such as depth and what you are holding, you can establish the size of the poles.

I'm not sure bow anchoring is needed if you just run two and it should be easier than messing with any anchors as you can pin spot on precise.

 

It is 3-4' in the summer, 2-3' in the winter (plenty of water for the vessel). I will sketch something up ASAP

 

The important thing about a spud anchor is that it needs to be driven into the bottom. So it will need a way to force it down, or the boat up, as well as raise it. This is why the commercial ones for bass boats are knee action; either hydraulic or lead screw. The big guys that are like you show are driven in with the barge crane

 

Well, bouncing off Hardiman a bit..if nothing else, a concept..

These (or like) could be in fixed mount and just drop into the seabed. Probably need more robust...

Greenfield® - Sandshark Ultimate 48" L Beach Anchor https://www.boatid.com/greenfield/sandshark-ultimate-48-l-beach-anchor-mpn-ss-u-lg.html?singleid=2941962869

 

Are you thinking a single spud or two so you do not have to anchor?
How many times a day would you use it? Or how many times per month?
Do you need the gunwales free for docking, Ie can the spud(s) stick out the side of the
boat or would it/they be mounted off the bow and transom

Two spuds would take away the use of an anchor while a single spud would need to be mounted close to the back to reduce swing. If a single was put on the bow, then the boat could still swing around the spud.

I would use square tubing for the spud as the measurements can be chosen to provide
higher bending resistance for the same or less weight.

If you are considering relatively low capacity winches to lift the spud, you have to consider that most of the small planetary winches do not offer much in the way of braking.

The cheapest method, though a little more labor intensive would be to mount say a 2 1/2 inch square tubing bracket ( by 3/16 inch wall) off the gunwale, when you get in position manually drop in a 2 inch square tubing spud. To push the spud into the ground, just run a hand winch off the deck, with the line going over the top of the spud, where you have installed a pulley, the line would fit into the pulley and back down to a hook on the deck.
Cranking the winch will push the spud down into the bottom.

Bush league but if not used often, easy to use, the spuds can be put out of the way when you do not need them


Alternatively,
1)to make it more user friendly, install 12 volt winches to load the spuds
2) if you want to leave the spuds in situ, or find the spuds heavy to lift, you could also position a loop on the spud closer to the bottom of the spud and use the winch to lift it. Just by unlooping the winch line from the top pulley

Ensure that the spud has some opening on the bottom to allow water to drain out

 

We use a ton of 6' helix anchors, just a shaft with similiar head on it. maybe our fab guy can make a head on the actual anchor and we turn it in?

 

thank you! all great considerations. Fab guy is out of town for 10 days! but I want to bring ideas to him and look at costs, get a real drawing