Building Logs

On the Catwalk

Posted by Paul

Another month or so of work done and it feels like I didnt get much done, the work is quite fiddly and I get little to show for the work that goes in. The overall design for the catwalk was decided upon almost before I started building. As soon as we decided on the bi-rig in fact. What the rig gives us is an open forebeam, no stays means no triangular brace (called a striker, some call it seagul, some pelican, some dolphin, but all follow it with striker) that takes the load of the forestay and spreads it over the forebeam. The lack of this contraption means the forebeam is open.

We have a friend that would nose his 40ft cat into our local public wharf and we would have to climb up one of his bows onto his boat. That bow might be a meter taller than the wharf and a meter out from it, so a jump and a climb was the order of the day. I could do it, but it wasnt the most graceful entry, and Jo could barely do it. As we get older that mode of entry to the boat wont work at all. And it was about this time that I hit on the idea of a gang plank over the forebeam onto the jetty instead. A far more dignified way to board a cat that noses into a jetty.

So when I originally built the catwalk I was sure to make it a 100mm deep box to house a ladder that could swing out over the forebeam and down to the water, and under it, on the same hinge pin would be a gang plank that would swing out over the top of the ladder, the ladder resting on a jetty and then the gang plank sitting on the ladder as its brace to stiffen it, and being hinged to the boat, the ladder and plank would swing up and down as the tide moved the boat up and down relative to the height of the jetty.

One of the complications of anchor deployment and retrieval is the shank and the shape of modern anchors such us the super sarca, manson supreme and rocna anchors. They have a round roll bar that self rights them so they self set as they drag along the bottom. This roll bar makes them difficult to stow. I was originally going to make a bow roller over the forebeam and then somehow (via a roller) direct the chain down to the flat catwalk but the complicated need to get the chain over the forebeam but below the height of the forebeam meant I shelved that idea.

Many cats have the anchor come up onto the catwalk via a slot in the catwalk usually with a stainless steel frame that is shaped to take the anchor shank. As I ran out of money some time I ago, all of my initial fancy plans for custom (I hate the word bespoke!!) made bow roller started to slip away and I have had to figure out a way to make an off the shelf bow roller do the same job. To motivate me further, I was given an old bow roller that just needs a new rubber roller, but is stainless steel, albeit 304 not 316, but beggars cant be choosers as my late great aunt Tess used to say.

The catwalk height/depth in relation to the forebeam and forward deck was set months ago when I first constructed it. Well, it sort of set itself. The catwalk depth is about the same depth as the forebeam is thick, so that the catwalk sides offer the same profile shape as the forebeam and the trampoline support tubes are constructed into the catwalk sides in the same way as they are in the forebeam (conduit glassed with 3 layers of glass with stainless steel rod inside then scallops cut into the conduit/glass to reveal rod to which the tramp will be laced) and this method was repeated on the hull sides and the foredeck). It worked out that the catwalk would be 100mm deep, plenty deep enough to house a ladder under  lid so that top face of the catwalk becomes the top of the lid. I also made the catwalk wide enough to house a ladder and a trough that the chain could pass through, so that I could hose down the chain as it travelled through the trough so that should the chain come up covered in mud, most could be cleaned off before the chain went into the chain well. The anchor would remain in the bow roller, secured with a pin of some kind.

So after much online research about how others have done this, and there is pretty much a different method employed by each boat builder, and seeing many up close at boat shows, I decided that rather than go over the forebeam I would come up from under the catwalk through a slot behind the forebeam. I would still need to put a bow roller on the forebeam in order to employ a mooring buoy and not have to thread the line under the forebeam and up into the slot. The bow roller on the forward edge of the beam would therefore allow the mooring buoy line to come over the forebeam and onto a cleat on the catwalk. It could also allow me to deploy an emergency anchor over the forebeam and still have it retreave via the windlass direct to the gypsy but my heights were a little out so a little revision was needed. More on that in a little while.

So first step was to design the bow roller sides onto the forebeam. I decided to use 5mm solid glass plates cut to shape then glassed with another 5mm of glass onto the forebeam. So I used my now trusty method to decide on a shape. Take photos of the way others have done it, so having taken said pics at the Sydney boat show a few weeks ago, I then made cardboard templates of a variety of different shapes based on the variety of different pics I had and settled on the one I liked best. I cut the solid glass to the template shape I settled on and then dry fit them to the forebeam to see them in place. Then I glued them on. Once glued on, I glassed each side of the plates with 4 layers of 450g uni and 4 layers of 457 double bias each side. This made them about 10mm thick each.


I set them apart 100mm in order to fit a 90mm roller. Once I had them glued and glassed Dean suggested that the loads on these would be enormous and that I should beef them up even further, so I coved a bigger cove and added some extensions to them under the beam and aft on the top side to shape them into the catwalk and gave them another 6 layers of each type of glass to the outside of each plate and 2 layers of each type of glass to the inside of each plate so now along with the 5mm of solid glass plate they now have 12 layers of uni and 12 layers of double bias each side and the glass plates are now 15mm thick each at the base tapering out to about 12mm thick at the edges. I figured the stress of the boat would pull from the inside of the roller sides to the outside each side as the bow pitched from sided to side so I put the extra glass to the outside of each side plate to better handle those stresses. I also glassed another plate onto the other side of the catwalk so that the hinge pin for the bow roller extends through to the other side of the catwalk and becomes the hinge pin for the ladder and gang plank.



I didnt bother to shape the underside of the ladder side bracket as it would only ever come under very moderate stress in that it only has to support the weight of the ladder and gang plank and the person travelling over it, maybe 200kgs tops, only one person at a time would ever go over it. So it can easily handle those stresses. The bow roller sides may meet loads of many 1000’s of kgs. I am pretty confident that the bracket will handle the load but you never really know until the boat has ridden out its first storm on a mooring buoy. But even if the roller sides were to fail, the worst that could happen is that the mooring line could demolish the side and then be able to slip onto the forebeam and slide along it, and of course damaging the paint, but it would still be attached to the cleat on the catwalk so the boat would not come adrift of the mooring. But if a comparison between what look like flimsy alloy bow rollers on some of the boats with an alloy beam are the comparison mine should be ok.

Next job was to cut the slot into the catwalk to take the stainless steel anchor roller. The anchor roller needs to be in a directly straight line to the windless so that the chain is pulled in a straight line from the gypsy through the anchor roller. The boat will pitch from side to side and be steered to the anchor under power but once the anchor chain goes over the anchor roller, the run to the winch needs to be straight. I have the anchor roller (Dean gave it to me) and he suggested I ought to have it angled down so that an anchor can be pulled up onto it and clear the underside of the beam and catwalk. So I made a solid glass mold of the anchor roller that I could glass into the boat to house the stainless steel frame on an angle protruding under the catwalk. I covered the s/s frame with clear tape and glassed directly onto it as a mold.


Once the molded glass anchor roller holder was cleaned up I glassed it into the slot at the angle that worked for me. I had to play around with anchors (I have a way over size CQR and access to an undersized Delta and also tried a Manson Supreme but its roll bar meant I could not fit it under the beam the way it is currently laid out, but the other 2 work) until I had it at an angle and in a position that worked. The deeper I have it protrude the better it can house each anchor under the beam, but the further out it is protruding the less substantial it can be glassed because less of it is in contact with the boat and more of it is just jutting out into the air under the boat. And the greater the angle the sharper the turn from angle to flat on the catwalk and the higher up it protruded above the catwalk. If it got too high I could not have a lid over the trough as I had hoped, and too high and it becomes an obstacle on the deck that can be tripped over. As with everything else on a boat it became a series of compromises until I had the best I could get that ticked all of my boxes. As it stands, an anchor with a roll bar wont pull up into the slot and be secured properly, so I will probably eventually get one of these modern anchors but only deploy it over the beam when the delta, my choice of standard anchor does not hold. I will also have that massively oversize plough that I was given. They dont hold very well so it will be my emergency anchor in the D section to go over the beam in the case of a dragging anchor in the hope it grabs enough to get the motors started and the main anchor reset. I also added a ply stiffening pad (25mm thick ply) under the catwalk to take any banging that may occur and to beef up the bolt points where the anchor roller will be bolted to the boat.


The angle and raised height of the end of the bow roller on the catwalk this created meant I had to rethink the chain trough. I was originally just going to have a ply wall either side and a ply base for it to skid along, that could be replaced if it wore out. But because it is now raised I needed a shallower trough that still fit in under the lid height of the catwalk once the lid is fitted. I thought about a pvc pipe cut in half but then realised I already had the shape, the mullion mold. So I made up a trough in the mullion mold 4 uni layers thick (about 3mm) and once that was set I started cutting out the D section and bulkhead that this trough needed to get through to bring the chain out beneath the windlass in the main anchor well. I made the trough over length so that the pieces I cut off could be used as lids to the trough to protect the D section and bulkhead. I had thought about having a stainless steel hawse pipe that the chain would travel through to get to the main anchor well and this would be flared at each end so that the chain could not catch on it. It was also to be slightly bent to subtly change the angle of the chain so that it emerged at the angle to the gypsy (because the gypsy is higher than the catwalk), But this has inherent in it a number of problems one of them quite serious. First is that anywhere chain rubs it will eventually wear. Also the pipe would be about a meter, and should the chain kink inside that pipe it could well jam in there and be unable to be unjammed by the winch, and Murphy will tell you, that jam would occur at the most dangerous and least opportune time and finally, metal on metal is noisy and rough. So by having the chain exit the trough at a continuous level means it can change direction up to the gypsy by a roller on the end of the trough in the anchor well, and it too can be replaced if it wears, simple and effective solution. Smoother, replaceable, and most importantly no way it can jam.

The mullion mold made a trough with flat edges that I could use to mount the trough. I knew the height the trough needed to be based on the back edge of the anchor roller frame, I then cut some duflex rails and glassed them into the catwalk at the height that would make the base of the trough the same height as the aft edge of the roller frame. I set it at level. I was going to have it tilt slightly so water would run out of it but the boat pitches so much that what is level? There will be drain holes along it and the well has a drain hole too of course so it doesnt really matter where the water goes, it will find its way out.


The easiest way to cut away the hole for the anchor trough was to drill a series of holes and then use the drill to cut the small way between each drill hole until the mass is moved. Its a slow time consuming method but because of the angles and spaces saws wont fit. A die grinder may have worked but I found the drill working so I went with it. Once it was all cut out, and the trough dry fitted, I glued and glassed it all in. The point where the anchor chain changed direction from the angled anchor roller frame to the chain trough is a point that will wear, so I set the chain trough back 100mm to leave a void. In that void I will put a nylon pad. It will wear but is designed to, and will be replaceable. The final piece of construction on the catwalk was to glass in a ply side wall that separates the chain trough from the ladder cavity and also provides a hinge point for the lids. Two lids, one narrow one over the chain trough and the larger one over the ladder. I intend for the lids to be able to be kept closed or open and the anchor deploy or retrieve to work and for the lid over the ladder to be able to be closed with the ladder deployed or not.






Because there may be times when an anchor is deployed over the beam it will need to be retrieved over the beam and I want to be able to use the windless to bring the anchor up in this scenario. I used a long aluminium pole I have to run a straight line from the gypsy to the likely roller position. I have made the bow roller plates large enough to take a roller and a pin above the roller to hold the chain or rope in the slot so that if the bow drops in a wave trough the chain or rope cant come out of the slot and run along the beam. So the roller will be low in the slots. When I ran the pole from the gypsy to the roller, it just touched the hatch bottom edge. I dont want to have to re-shape the hatch opening and lid so the easier solution is to raise the winch on the table inside the hatch. But I cannot raise the winch much, because then the hatch lid wont shut. I managed to raise it enough with just a 20mm ply pad between the winch and the table so that the chain would clear the hatch edge and still be low enough for the lid to close. But this increased the angle to the chain trough, which meant I had to reshape the table slightly so the chain clears its forward edge on its way from the roller that will change its exit angle from the trough to the gypsy. All these small changes were easy fixes but highlight how one change has implications for others.



The next step to finalize this section of the build is to make the ladder. Yes make it. I cant find one the exact size I want, that is they are either too narrow at the top, too wide at the base, too long or short or 3 of the 4 (it would be hard for a ladder to be simultaneously too long and too short!). The other issue with commercial available ladders is they are not made for the marine environment. You can get them with fibreglass sides, electricians use them to minimise charge grounding through them into the ladder, but they use aluminium rungs bolted to the glass sides with steel nuts and bolts. In the marine environment that would last a few months at best.  And the glass ladders are simply glass U beams made from chop strand. So I will make 2 glass U beams with uni and double bias on a simple mold of a timber rail. Then I will make rungs the same way but just slightly narrower mold so that the rungs fit inside the side rails, and then glass it all together so there is nothing to corrode, and I get to make it the exact width at the bow (400mm) and aft end (500mm) and the exact correct length to fit in the cavity (2000mm) with one rail square to the rungs the other side tapered to the width top and bottom, again to fit the cavity. Below is a mock up using one of my cheap ally ladders to show the effect I am after and the first rail on the mold. And I can build my exact size ladder for about $20 instead of the $200 a similar good fibreglass ladder would cost.


Once the ladder is made I will need to make brackets that run over the forebeam to the axle that will run through the 2 bow roller sides and the bow roller itself to the plate on port side. This axle is a 3/4 inch solid stainless rod. I was going to have thread tapped into each end or just have a hole drilled in it and a stainless split ring each side. There wont be any side to side pressure on that axle. The brackets will need to be strong, strong enough to easily carry 500kgs. Not that 500kgs would ever be on the ladder or gang plank but you have to have a margin of safety built in. And then once all of that mechanics is made the lids can be made and fitted to finish that section of the build until fairing and painting.

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1 Comment

  1. Karel Michielsen

    after experiencing the loads the anchor can put on the fore beam (in my case one with fore stay taking the load) I’d check with Schionning to ensure the beam can take the load of a stuck anchor pulling the boat into the water until something breaks. I reckon the load can be several tons.
    Also the sideways forces on the roller during retrieval are very destructive and best avoided by having the helmsman manouver to keep the chain approach reasonably straight (we call the signalling between anchor retriever and helmsman the chicken dance as we do it by arm signals)
    Are you taking the load of the rode with a bridle during mooring / anchoring? Suggest you do, plus chainlock to keep the load of the winch in case the bridle comes undone.
    Enjoy the fun building and don’t be in to much of a hurry to replace it with the sailing adrenalin, Karel

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