Friday, October 08, 2010

Net Beam, Anchor Roller, Cockpit, Motor Mount and Deck Mock-Up

The weather has been spectacular here in Mississippi since I moved my hulls out of the shed.  They haven't seen a drop of rain so far, and the humidity has been low and the temperature just right for epoxy to cure.  I'm working on a lot of miscellaneous projects that had to wait until the boat was assembled for correct measurements and final decisions on details.  One of these projects included mocking up the cockpit by temporarily hanging the side panels in the space between the mast beam and the aft beam.  I was then able to screw a temporary 2 x 4 in place to represent the height and fore and aft placement of the motor mount, so I could check clearances and make sure it would be the right depth in the water when down and still tilt up high enough clear the surface when sailing.  The motor I'll be using is a Nissan 6HP Extra-Long Shaft 4-Stroke. 

I think it's going to work out fine in the space shown for the motor well in cockpit drawing in the plans.  Because of the 25-inch shaft, I can mount it a bit higher, which will help prevent it from drowning out in big waves.  It will still be pretty low overall in relation to the top of the aft beam, as you can see here:

The 25-inch shaft will keep the prop deep in the water, with cavitation unlikely.  Mounting it forward of the aft beam will also help with this and with proper weight distribution.  The board laying across the skids that the hulls are resting on in front of the prop shows that the prop can't hit bottom before the hulls do. 

I've also designed and built the aft net beam in the past few days.  I scrapped the idea of using the aluminum pole I had for this, as a wood-composite beam will be easier to mount things to and to finish in a way that matches the boat.  I used a V-shaped lamination for the bottom, fit into notches cut in the stern post.  The other board is the inner top plate, beveled to fit into the V.

Here is the next assembly step, putting the inner top plate in place with epoxy.

This  view of the unfinished end shows the final cross-section of the beam.  Built of Doug fir, it's plenty strong and stiff while still lightweight because of the hollow area.  The piece of wood on the forward edge that stops at the inside of the sternpost is a teak trampoline lashing rail that will be drilled on 3-inch centers for the aft tramp lacing.  I'm using teak for all the  lashing rails as the holes will be exposed to the weather and most other woods would rot in this use. The sharp edges of the beam corners will get a smooth radius and then the entire beam will be sheathed in fiberglass cloth.

Here's view looking aft to show how the beam fits.  The triangular design with the low, flat top will allow plenty of clearance for the tillers.  There's a lot of usable space back there between the sterns and the aft beam.  I can't imagine not having a net beam to take advantage of it.  Mine will have a drop-down ladder in the center with tramps to either side. 

Anchor handling and storage is often overlooked in the building phase of these boats, but any cruising boat, no matter how simple, relies on good ground tackle, and that ground tackle must be accessible and easy to handle.  To that end, I've built a custom anchor roller for the forward beam that nicely accommodates my 22 lb. Delta plow anchor.  Anchors in this configuration are difficult to stow anywhere but on a roller, as they are bulky, awkward and take up too much space inside lockers.  The roller housing is assembled here for fit, but will be removed for finishing before it is then filleted and glassed onto the beam. 

Here's the anchor, salvaged from my previous boat, a much heavier 26-foot monohull.  The Delta should be more than adequate as the main anchor on the Tiki.  If I were buying a new one, I would probably go with the highly-regarded Rocna design.  As it is, I have this one, as well as a smaller CQR and a large Danforth.  All three will be on board with appropriate rodes.  At the top of the beam, there will be a teak block to receive the shank and hold it in position, and a cleat to secure it with a short line through the forward eye. 

Another big project will be building the slatted deck forward, between the mast beam and the forward beam.  I've decided to go this route in lieu of a trampoline, as it is so much better to work on and will last longer.  It will also cost about the same or less, as I have ordered locally-grown select-grade southern bald cypress for the material.  I considered teak, like David used on his Tiki 30 forward deck, but prices have really gone through the roof, especially for what little teak is available in my area.  The cypress will be lighter weight anyway, and should last a long time with care and proper construction.  Below, I have mocked up some of the longitudinal stringers out of scrap wood just to get accurate measurements on the amount of material I will need.  The longitudinal stringers will hang under the mast and forward beams.  Then deck beams across will support the planking, which will put the top of it about even with the built-in ledge on the aft side of the forward beam, making it about 3 inches higher than the adjacent decks on the hulls.  The whole assembly will be easily removable as a single unit to aid in disassembly of the boat.


Randy Anselmo said...

Looks great Scott. I'm grappling a little bit with aft netting design. The Espresso came with a reasonably well-built center frame and boarding ladder, but they're very heavy. I'm considering netting the entire space to save weight, and increase usable space. I'm also considering using bamboo for the aft net beam. I'm a little surprised I haven't seen more bamboo in use on Wharrrams, being based on polynesian design principles, after all. Probably difficult to come by in England. My father-in-law scavenged me a nice (brand new?) retractable ss boarding ladder that I can mount on the beam.

I've had similar thoughts on the anchor roller. Will you build a chain/rode locker on your forward deck? Are you at all concerned about the weight distribution of the wooden forward deck? I've been looking at materials for replacing Espresso's tramp, but hadn't considered a hard deck.


Scott B. Williams said...

Hi Randy,

I think some people have used bamboo for various parts. It could work for the netting beam, but I'm not sure how long it would last.

I probably will build a rode box under the forward deck as David did on his Tiki 30. I'm not concerned about weight on the forward deck as these designs tend to be stern heavy anyway. I'll keep the deck as light as possible though, with plenty of space between slats to allow quick drainage in breaking waves.

Mayberry said...

Looking good! She's really coming along. Hopefully I'll be in a situation where I can complete my skiff project in the not too distant future. Meanwhile I'll live vicariously through your build...

Scott B. Williams said...

Thanks Mayberry,

I'll look forward to seeing it when you get back on your project. My work is sporadic but that's the way it has to be now. Hopefully I'll make the final push to completion in the spring.

ItsaGamble said...


Your build looks great, she is coming along very nicely. I was considering building a aft beam for Element 1 as well. I was initially drawn to the idea when trying to figure out where I would put a self steering system that would be out of the way of the tillers. Once I started thinking about adding a beam the idea of the added deck space made the plan make even more sense. My question is what are your plans for securing the beam to the hulls? Will you mimic the lashing design used on the rest of the beams or did you have something else in mind.


Scott B. Williams said...


The aft beam will be lashed, but only on the inboard sides, as it is not structural. It will be locked into position laterally by the additional teak rail that is drilled for the tramp lashings.