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baDumbumbum
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Discussion Starter · #1 ·
Interesting challenge.:) Our Albin Ballad (30', 7200#) has precious little room on the bow for a typical anchor roller, especially one that would fit a 33-35# anchor with rollbar. Partly because it is a coastal cruiser & IOR racer aimed at Scandinavia and other daysailing locales. Partly because the pulpit is designed (as is common with Nordic boats) with a step-thru notch; many folks in those fjordal areas anchor off the stern and tie off to the rocky shores, bow-to. Also, this is a 1972 boat, before roller furlers became standard on the stem fitting.

At any rate, getting a mid-sized anchor to snake between two pulpit stanchions about 8" apart -- and under a lower crossbar maybe 10" above the deck -- is challenging, esp. when you mentally stuff a furling drum in there. So I'm pretty sure we want to add a modest anchoring platform. It will carry our primary anchor ready to launch nearly all the time. No windlass planned, tho that could change. I'd like to be able to drop it from the cockpit if required, and to lead the rode back to the primary winches via snatch blocks on the rail, if humping it by hand is too difficult. The platform must resist downward loads when the boat snatches at the anchor or a person is standing on the platform, some sideways load, and plenty upwards force: we intend to attach the strop for the 340sqft Code Zero at the tip of it.

Those requirements suggest a rigid bobstay (bobstrut?). So here is the design I have in my head right now, mocked up in poplar and PVC:

sprit3

It's not exactly graceful at this point -- I wanted a testbed (barely!) strong enuf to actually lower and raise the 22# plow, which is standing in for some future Rocna. 1.25" thick wall stainless tubing is the plan (round, or square tube?). With this design, the anchor will pass either inside or outside the pulpit stanchion. Outside is appealing cuz there's more swing length there and less chance of interfering with the roller furler. Any good reason not to lead the rode as shown? What sort of chocks, and where should we put them?

Anchor fully up & stowed, in profile:

sprit1

Here you can see two big challenges: will the rollbar clear the end of the platform? And the bobstrut angle. Oy.:( Love those IOR knife bows, but how the heck do you get a decent angle on that thing? Yah, I could move the stem attachment point down and gain a bit better tension/longitudinal compression ratio, but since the bow keeps running away from you, each foot lower only nets you, like, two degrees. I'm expecting upwards loads of maybe 1000# on the Zero.

Lastly for now, this is just a profile pic with the chain deployed (pls ignore the foreground chain):

sprit2

Forsee any problems at anchor with this setup? I really appreciate the guidance you experienced anchorers can provide.
 

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Senior Citizen
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Will you leave the rode over the end of the 'sprit roller at anchor?

While sailing aboard a Fuji 35 with a plank style bowsprit, I was taught to deploy the anchor off the roller, then route the rode outside around the pulpit, bring it back to the gunwale and over a cheek block on the outside of the gunwale, then to the cleat. Downforce on the end of the 'sprit was eliminated.
-CH
 

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baDumbumbum
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1,142 Posts
Discussion Starter · #3 · (Edited)
We'd have either option. But mostly we want to anchor straight over the roller, as most folks do in most conditions. The roller will need fair leads (no chafe) for that. In jouncy conditions, we could always tension a spare halyard to the end of the platform, too. Also, if we move the chocks back, we could add snubbers or even a bridle thru those to unload the roller. Tho at this point, we are planning only 35-50' G4 chain & the rest 8-strand nylon.
 

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Bristol 45.5 - AiniA
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You have choices of 'next-gen' anchors without roll bars. Had the pleasure of meeting Peter Smith the inventor of the Rocna in Namibia of all places and he had a custom-milled version of a new anchor without a roll bar that Rocna are building for West Marine. It should be in the stores this year and will be branded as a West Marine anchor. Manson make a similar one.
 

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I will be doing the same on my boat soon. I will use round heavy wall ss pipe. I don't think square stock would look very good and haven't seen one made with square stock. I don't have your issue of as large a forward overhang to deal with luckily.

I think you may be better to use a single roller as close to center as possible with the anchor shank beside the forestay if possible, maybe raising the furler drum to clear if it can be done.
 

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Master Mariner
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We use a snub line, brought aboard through the stb forward chock, alleviating any strain on our bowsprit (anchor rollers) when anchored, even in the roughest conditions. Your biggest worry is dragging whatever you put out there, through the seas when beating hard to weather. I have seen many a bowsprit or anchor rollers, broken when an industrious owner builds too elaborate a walk way and/or anchor roller system on a bow not designed for those stresses.
 

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I agree with the post about using round tubes, not square; much stronger. An open platform without walkway so the seas can pass right through when you bury the sprit into a wave. Strong backing plates inside. The bob stay should also be a tube, not a wire as you don't have top support.

You need to think through how you will run the rode. Do you plan on a windlass? If so, run the rode straight back with appropriate sized and backed chain stopper. The chain stopper takes all of the pressure from anchoring, not the windlass. With 50' of chain, you will need a snubber to absorb the shock from waves. That should be run back to a bow cleat through chicks. That eliminates pressure / load on the sprit and gives a lower angle for better holding.

It looks like you will be able to fit a next gen anchor on your sprit. I enthusiastically recommend them!

Good project!

Tod
 

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Hi Bob,

I think it looks fine. But i am neither an engineer or a bowsprit owner.

But the thing I know is that worthwhile projects give you a definite advantage to your cruising life.

If your anchor platform saves space forward plus lets you but a roll bar new gen anchor the you will have succeeded well.

I cant see why it wouldnt work, or the pressure on the bow would be too great with the strut. I doubt you'd need to snubber direct to the bow fairlead, but you might find its a bit more convenient, you wont know till you are in the water.
 

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baDumbumbum
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Discussion Starter · #12 · (Edited)
Not much on the square look...

Take a look at these pictures from klacko marine for some ideas; their work is beautiful.
Klacko Marine Hardware

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It's a mockup, Bene. I built it in twenty minutes.:laugher The final object will have radiused corners -- if only cuz I sometimes run into things....:eek:

I love the looks of tapering (wedge-shaped) platforms, but with fine-entry boats like ours, flaring the shape actually creates really negative consequences at the upper attachment points. You end up with all the compression forces running parallel to the bulwarks -- which vastly multiplies shear on the fastners, leverage on the fittings, and spreading forces on the sprit crossmembers. I did some scratch-pad calcs & was surprised at how rapidly stresses increase with a trapezoidal platform shape. Also less room at the pointy end for a second anchor. Doubt we'll ever carry one up there, but it's a possibility we might retrieve two, side by side.

BTW, since the photos lack any kind of scale: the mockup is 17" wide by 30" OAL. Projection forward of stemhead is 15". We could maybe shave an inch off the width and 2" off the projection before stuff starts bumping into stuff. If we went with a single (near)centerline anchor roller and trapezoidal shape, the forward end would only need to be 12" wide or so. Would look a lot like this:

Although you'll notice, this Monsun31 hasn't got the lower pulpit legs to deal with.;) Thanks for all the ideas so far & keep 'em coming!
 

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Square stock and anything else you might want...cut to size
You need it professionally welded so you might as well use round stock for both its strength and looks. I have seen only a few using square stock and they didn't look professional - no matter how good the welds were. Makes one wonder where else shortcuts or unprofessional work was on the boat.
 

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baDumbumbum
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Discussion Starter · #14 ·
I may be running into a similar situation soon myself. I personally would not want to build an anchor platform. But I'll be interested to see what you come up with. Are there any anchors that will fit your boat without the platform!
I'll farm out the welding to someone who knows what they are doing.:D If we keep building 20-minute prototypes incorporating the advice offered here, eventually one will stand out as the best design. Then I'll mock it up in welded 1.25" EMT & test it again. If satisfied, I'll possibly shape the stainless tubing myself & take it & the final proto to the welder & say, "Please weld these bits into this."

This person did an amazing job restoring a trashed Ballad. His boat had a custom stem fitting with integral roller on one side (that is a possibility for us!). But he found the largest claw/plow/spade anchor that could fit on it is 7kg -- and that the smallest commercial roller that could handle a 10kg or bigger anchor is too wide to fit on the Ballad's skinny bow. So he is using the 7kg claw for his bower & will hand-launch bigger hooks at need. (We want a larger primary ready to deploy when sailing coastal.)
 

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Peter (Mostly about Boats) is a friend and customer. He has done an excellent job on the Ballad and the Vega he owned previously. He has even made some of his own sails.

Here are some ideas from neighbor's boats. The first is a short unsupported platform on a CR400. It doesn't project very much.



The following shows a platform on a Pearson 424. This is what I will probably pattern mine after.







Notice that on both boats the furler drum has been raised high enough that it doesn't interfere with the anchor shank. This allows the anchor to be close to the centerline which is best for both loading and lead to the winch - or chain stopper or cleat.
 

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baDumbumbum
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Discussion Starter · #16 ·
Thanks, Brian. That's excellent help. Longer link plates are probably required on our furler anyhow. Not thrilled about that, just because it complicates the furling line lead somewhat, but a decksweeper just isn't realistic or (honestly) justifiable for us.

That Pearson's rollers look kinda industrial, but there's a lot to be said for putting them high & forward. Sprit can be shorter, bobstrut angle is better, and the rollbar issue is solved -- nothing for it to hit! What keeps the shank put, tho? Most deck-level rollers have long steel channels to assist w/that, and positive shank locks in one or two places. Seems like that heavy CQR would be wallowing away up there like a live fish.
 

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I agree the Pearson platform isn't ideal, maybe not finished totally. As far as height of the platform I think I would want it as high as possible and for it to follow the sheer. It looks wrong when you see one either drooping or aimed too high.
 

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baDumbumbum
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Discussion Starter · #18 ·
Okay, dumb question: what wall thickness on the tubing? You can get polished 316 stainless tubing in Standard (0.049), Heavy duty (0.065), or Gronk-Pruf (0.12) wall thickness. I'd be game for the thicker stuff since the platform isn't that big ... but do ya think a tubing bender could handle it? That's pipe, almost.
 

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Bob, if you have a local stainless shop in mind, ask them what THEIR tubing bender can handle, unless you also have one. Same question, what is it rated for? Odds are slightly in favor of the shop having one that can handle more than what you'd buy for one project. (G)
 
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