Single point lifting sling for Rowan

[James McMullen]

Another one of the projects I worked on over the winter was a new, simpler way to launch and retrieve Rowan from a crane or hoist. The Cap Sante Marina here in Anacortes has a crane down on Q dock which is not only very convenient from my house, but is also much cheaper than the launching and parking fees at any of the other launch ramps here on Fidalgo Island. Plus, it's kinda nice not to dip your trailer in the salt any more often than you absolutely have to.

I had made a more conventional sling last year with webbing straps that wrap around the hull and big aluminum spreader bars--seen here putting Big Food in--but it is a bulky and awkward thing to stow if I were to need to bring it along with me. And I do have some romantic notions of hoisting Rowan aboard a fishboat headed up the Inside some day. . . .I wanted something quicker and lighter and foolproof, something easy to pack, and something that was very quick and simple to deploy.




I had just made some jacklines out of Amsteel Blue for a client, and so it occurred to me that a lifting sling out of the same stuff was just the ticket. This stuff is much stronger than steel cable of an equivalent size, and much lighter and easier to handle to boot. The only issue with it is that the fibers are so slippery that you really can't trust tying a knot in it, nor should you use conventional, simple splicing methods. But I'd already just practiced the locking Brummel Splice a half dozen times, so a few more were no trouble at all.
I decided to use a three-point attachment as it is much more inherently stable than a single or two-point system. These padeyes are each individually rated to hold six or seven Rowans all by themselves, but I figured it wasn't worth skimping here. It was a little tricky to figure out just where to place them where I could most easily tie into structure that would help distribute the load, yet be out of my way completely when not in use. I settled on mounting them on the bulkheads where they would have fillets and flanges every which way reinforcing and distributing the strains through the monocoque glued-lap hull.

aft:


and fwd: As you can see, they are color-coded to make it very easy to know which goes where in a jiff.


The stainless steel carabiners make for an instant and secure on-off. And the whole things stows inside a tiny little stuffsack so I can just bring it along wherever I go in case the need should arise. It took a little bit of fussing to get the lengths just right so it would balance where I wanted it, but don't let me leave you in suspense--here's Rowan. . . .in suspense.

[James McMullen]

While I had her up there, it occurred to me that I'd always been curious to see what her foils looked like extended, as I never get to really see them that way. So here's what the ol' girl looks like from a fish's perspective:



and from aft:



and from head-on:



If anyone is curious about how to get some old-fashioned-looking rowboat to actually sail like a witch, please refer them to the preceding photographs.

[htom]

For her next trick, Rowan dons a Rogallo wing and becomes a flying boat.

[potomac]

That looks great, James. It's remarkable how much this boat continues to evolve as you fine-tune your ideas about what your ideal boat is. How much stress do you reckon is on those points? Or more to the point, if you were considering storing Rowan suspended as seen above, only higher, would you use this system or a more conventional under the hull sling? It seems like a great way to free up room in a space that does double duty as shop and boat house.

[Gerarddm]

Wicked lookin' foils, man. Is your rudder oversize from The original plans?

[skaraborgcraft]

I can understand why you went for 3 over 2 attatchment points,but i would have gone for 4 and matched the fittings in your aft bulkhead to better spread of load. Well handy if you ever find yourself in a helicopter winch recovery! Does that amsteel have any kind of streeeeetch in it? Cheers

[Binnacle Bat]

I can understand why you went for 3 over 2 attatchment points,but i would have gone for 4 and matched the fittings in your aft bulkhead to better spread of load. Well handy if you ever find yourself in a helicopter winch recovery! Does that amsteel have any kind of streeeeetch in it? Cheers

Four lifting points would require some sort of spreaders, eveners or what ever, or the loads would not be distributed evenly, unless you were incredibly precise in your splicing, and using stretchy line.

On the lifting bridles I have seen, the lines are longer, and the lifting points a little closer together. The angle of the lines in James's rig means that each one is carrying a load significantly higher that one third the weight of the boat. The line and hardware may be up to it, but why put the extra strain on the boat?

Allan

[James McMullen]

Well. . .one third of the weight of Rowan is like 150 lbs or so and them ropes is rated for over 8,000 each, even with the splices. It's always a compromise though. Out at the bulkheads like that keeps me from stepping on them anyways.

[Ian McColgin]

Well done.

I would have been tempted to lift from two points at the front top and back top of the centreboard but that might not have been so wonderful. I do lift the Thistle on a sling run through the CB trunk when the board's out.

[Binnacle Bat]

Well done.

I would have been tempted to lift from two points at the front top and back top of the centreboard but that might not have been so wonderful. I do lift the Thistle on a sling run through the CB trunk when the board's out.

From what I've seen, standard lift points on Thistles are each side of the grating at or just forward of the mast, almost out to the gunwales, and a ring on the ramp on the back of the CB trunk, or on the keelson just aft of there. I haven't managed to get #1609 to balance as nicely as Rowan does, as I don't have the headroom in the barn that James has in his shop. Just as much stuff, though.

Allan

[Ian McColgin]

Oh yeah. With the board in place the Thistle is a brute to lift especially if the overhead is low. What I did only works for a stripped hull with no board in place.

There are many different lifting problems. One of the cleverer problems I resolved was to lift a boat off the trailor and raise it 6' to the garage rafters.
This would give enough room for the car to get under or to walk under. The trailor was stored on it's side under the eves outside.

I arranged four very strongly mounted blocks hanging under the rafters at the corners of how I wanted to sling the boat with two athwartships slings. The flat strap slings met their respective lift lines in a D-ring and shackle connection to the lifting ropes such that the connection was right at gunnel heights and the lifts for each side ran straight up to the blocks, through and connected to a shackle such that when the slings were placed under the boat and attached all was about hand tight and the lift ropes ran straight to each other from pulley to pulley. From the shackle connecting the lift ropes a line ran under the rafters along the boat's center line, connecting to the forward ring connecting the other two lift ropes for the other sling, and on to a pully on the garage wall, thence down to a firmly mounted trailor winch. The single line was simply reeled up on that winch. It took about 7' of line take-up to lift the boat 6', which meant that was also the minimal distance required between the sling closest to that wall and that wall. The trailor winch was the only practical way to take up since a block and tackle would take up too much horizontal distance. Worked a treat for a light boat. I'd not do it with anything heavier than 200# empty weight and even for that I put some fore and aft bracing on the rafters to accept the changing loads from those hanging blocks. To save wind-up space, the line from the winch to the closest sling ring was actually cable.

Fun with geometry.

G'luck

[the_gr8t_waldo]

why didn't you just loop the slings thru the fwd/aft water tite bulkheads? two point lift, a 3point could be rigged, i'm sure, without any stainless hardare. being bolted to the boat. might i add that the aft sling(s) look like they are at a fairly low angle...the load on these porbably doen't exceed the amsteel rated load but the angle could result in suprisingly large numbers well beyond 150 lbs of the boats 1/3 weight. just out of curiosity, did you get to measure the angles of the slings, while suspended from the hook? have to say, i always enjoy seeing youre boat and the various projects.

[BBSebens]

I've lifted the aft end of Matty by her drain hole before. I just ran the line through the plug hole and tied it onto a short piece of shaft stock. Worked a charm.


Personally, I think I would have mounted the forward one straight to the keel, but the whole thing is probably so over-engineered that it wouldn't make a difference.

Now you have even less excuse to not go sailing! Perfect.

[Y Bar Ranch]

The angle of the lines in James's rig means that each one is carrying a load significantly higher that one third the weight of the boat.

The angle looked about 45 degrees or so, resulting in about a 50% increase in the load on each line over vertical. Not hideous.

[Eric Hvalsoe]

I love these pictures of Rowan.

My brother in law uses a four point sling on his traditionally built HV 13 - not a glued up monocoque structure, no bulkheads. A couple of times I have set up a different sort of system for clients - call it two+. This consisted of a strand forward and a strand aft going to keel through bolted eyes. Port and starboard strands midships provided stability. The keel strands carried the weight. True, if not perfectly calibrated and depending on what is sitting in the boat where, port and starboard strands will be weighted unevenly. But these are not the load bearing elements - those are going directly to the keel. All from a central ring.

[James McMullen]

I kinda just copied the typical angle I saw on the dinghy hoists on big boats around here. I could add more rope to change the angle pretty easily though if it seems to be a real stressor. But there's certainly a real practical advantage to keeping the head space to a minimum and no taller than it needs to be for use with short cranes.

I'm pretty sure I'm over-engineered to the point of super-serious extra redundancy, but that doesn't mean I wasn't watching and listening and double-checking very carefully when I first picked her up. And each time since, for that matter.

[James McMullen]

Answering questions:
Potomac, I suppose I could store her suspended that way, though it had never occurred to me. I'd rather store her on her trailer ready to go at a moment's notice, though. Having her on call for instant deployment enhances my mental state, even if I'm not quite ready to go myself.

Gerard: the rudder is sized according to spec. I think some of what you are seeing is just the perspective, but yes the rudder is wider and a lower aspect ratio than the CB. This is all according to plan for a rough-water capable boat as too high of an aspect for a rudder is far too prone to ventilation and stalling when you're getting tossed around and your stern pitched halfway out of the water. High aspect foils require consistent flow to do their best, this shape is less fussy and less likely to lose its grip in the chowder.

Skaraborcraft: Amsteel doesn't really have any stretch to speak of, not on the practical level. It is really stout stuff, stronger than steel.

gr8t Waldo: I wanted something that would be as instant as clicking on a carabiner. The padeyes seemed like a small price to pay for convenience. Besides, I get them for wholesale.

[WI-Tom]

James,

Don's Alaska plans show attachment points for load slings centered on the keel, one forward and one aft. With only two points like that, do you think the boat would balance, or would it be advantageous to arrange an extra line from each gunwale to the hoist point to keep it level as it's hoisted?

Thanks,

Tom

[James McMullen]

Tom, I think you need to have a check-line to each gunwale to be on the safe side. That's what Eric Hvalsoe did. I thought about doing that, but I decided I liked the three-point concept even better.

[WI-Tom]

Thanks--that'll be simple enough.

Tom

[Eric Hvalsoe]

Read #15 again Tom. To put things in persective, lifting the structure of Rowan, or a strip planked Alaska for that matter, is a slightly different proposition that a traditional plank on frame. And yes, any small unbalasted craft that is picked upright merely by the keel will want to rotate about 90 degrees, that is, stand on her gunwales. Thus the thwartship stabilizers to augment keel pick points. If you can structurally get away with a three point system like James', that is dandy. I had a client go with three points on a 10 foot plank on frame - two at the transom and one at the stem. I was about 90% ok with that. It has worked out fine. A much longer open traditional boat, I don't think so. And four points from a central ring to the gunnwales induces the kind of strain I would not care to inflict on my boat, even though I know she could handle it. In a keel pick system I imagine putting those eyes right about where you want to put a pair of sawhorses when the boat is in the shop - of course with necessary allowances to interior arrangements.

No doubt you've got your system nailed James. We understand that a relatively low central lift point is a matter of convenience, but also puts exponentially more strain on the individual components.

Come to think of it, bro in law does have a keel and stabilizer system. He occasionally carries a 13 on his cruising trawler with a davit.

This is a great reminder that I should do the same for my boat.

[WI-Tom]

Eric,

thanks. A question: what do the side stabilizer strands attach to? Are they taking so little weight that you can just lash them to the gunwales somehow, or is there a more complicated weight distribution scheme going on that I missed?

My need to ever use this is a long way in the future, but it's nice to think ahead.

Tom

[Yeadon]

They're just tied to the inwhale, mostly for stabilization. On Eric's boat (and mine) the rail is a great spot because it's riveted together versus screwed.

[Eric Hvalsoe]

I agree with Tim. Although for a more finished looking product I have made slings with clips going to thwartship padeyes, screwed through the inwale into the outwale. I emphasize that the keel should bear the brunt of the lift. There is nothing very special about the stabilizers, they simply keep the boat from rolling and need not bear a great deal of weight. Traditional gunwales are trypically rivited through. That may not be the case with your boat Tom.