Thread: OzRacer Build in Massachusetts, US

Originally Posted by planthire

Hey all,

I've decided that it's time to get my family (4 kids under 8) into sailing and get myself back out on the water, since I haven't been sailing for about 15 years. I grew up sailing in 21' (and later a 27') sloops on the Chesapeake Bay, and now that I live in New England I really think I should take advantage of the amazing sailing we have around here.

To get things going, I'm going to take the plunge into building an OzRacer, with some help from my kids where possible. The goal (like so many people here) is then to move into something a bit nicer like a GIS, then finally onto a 'full sized' family boat. This is pretty much a 10-15 year plan. Right now, I'm hoping to get my two oldest kids (8 and 6) onto the water with me this summer.

I have minimal woodworking experience, only what I would call the 'handyman' class of woodwork. I've built 20x20' decks, chicken coops, small wooden toys and wooden play-stands. I'm not totally incompetent, but I've never really tackled anything that required more than a few cuts. So, even the OzRacer is going to be a challenge at first.

I've bought and have been studying the plans and think it all looks workable, thanks to the high-quality of the build instructions. As I'm putting together my list to start sourcing materials here in the Northeastern US, I had a few questions I thought some folks could chime in on. I've tried to read back through all of the PDR build-threads here and in other forums, and I've spent a lot of time bopping around reading building info for other boats. Here's what I'm pondering:

1) For the plywood, I have a local marine plywood supplier available but their pricing is retardedly high. Would it be inadvisable to use 6mm marine ply (okoume, merranti or similar) for the bottom, then 2 sheets of 4mm exterior ACX plywood from a local lumberyard (not big box) for the remainder? I plan to precoat the plywood with epoxy, so it should be sealed well.

Some basic level marine ply is really nice for the bottom. But if you could get some five ply in 6mm (1/4") in exterior ply that would be OK too.

The rest of the boat can be 3/16. Also if you are interested I am about the release the plans for a simpler version with less solid timber in it. PM me if you are interested

On Peter Hyndman's blog Bolger's Brick became a Puddleduck, then a PDRacer, now it's a Kiwi PDR, Catbox and an Ozracer!

Oh .. avoid douglas fir plywood.

2) In the materials list (I'm looking at imperial), there is a listing for gunwales/chines (3/4 x 3/4, 8ft x 4) and chine log laminations (3/4 x 3/8, 8ft x 4) -- what is the difference here? In reading the directions, it looks like the latter is used for the chine logs (to build up a 3/4 x 3/4 laminate), but I'm not sure where I see the former being used for the chines.

Yes ... you need two 8ft 3/4square for the gunwales. The Chine logs in the OZracer Mk2 are just a bit tight to make of one piece ... Some have broken. It is pretty easy to glue up the laminations and be failsafe.

3) Is there any timber that could be used directly for the chine logs, rather than laminating two pieces? Spruce isn't particularly bendy, but if you steam it or let it sit in water (say, in a length of PVC pipe) for a few hours, you can definitely bend it to fit this curve and then let it dry. That would seem to be stronger and more resilient than the laminating method. Thoughts?

That's always my problem. I have to give failsafe directions. If you had some nice straight grain cedar it might just do it. But would need to be straight grain ... not with the grain wandering out the sides of the piece halfway along. And then it still might break.

4) Can anyone see any downsides to using composite materials for making the foils? While some of the rudders and centerboards that I've seen made are beautiful, it seems like you could get a much stronger, accurate and lighter foil using polystyrene (blue, more expensive but can be hotwired) or urethane foam cores and 2 layers of BID glass cloth. This kind of composite construction is used in making aircraft foils, so it seems like it could apply here, even though the same degree of accuracy isn't really required. Total cost would probably be closer to $150 (USD) for the rudder/centerboard (foam, glass cloth, epoxy), which is higher than Mik's suggested cost of $50. Thoughts? I'm more thinking of post-OzRacer building, since it would probably be overkill for this boat. It may also just be sacrilegious to use a composite piece in a wooden boat, I realize.

No sacrilege here! But I am sure it will be way more labour than the simplified foil section I use. Also foil cored blades are tricky to make as they tend to fold ever near where the skin is compressed on the corner of the centrecase slot where the foil exits the hull. The timber one is light enough and bulletproof. It will work out of the box effectively forever.

5) Ignoring my thoughts on using composite materials above... what kind of alternatives should be considered in the US for the foil staves? WRC is called out in the plans, with alternatives being hoop pine and Kirri -- none of which is readily available in the US. Edited to add: Okay, I'm stupid. I found WRC, it's available everywhere. Any other possible alternatives, though, just for posterity?

Western Red Cedar is the best choice for North America.

6) We have a lot of lakes around, but we are also very close to the ocean. I know of quite a few sheltered areas for sailing in, and I was wondering if there are any considerations I need to make regarding jumping from freshwater to saltwater.

None Nice to hose the boat down after a day on the salt water. On fresh I just dry the boat after.

Finally, I recall someone posting an Excel spreadsheet 'shopping list' -- I'm planning to do something similar, but if anyone happens to remember what thread that was in, it would be most appreciated! (It may have been for GIS, now that I think about it)

That's it for now! I'll be sourcing my materials over the next week or two, hopefully picking some bits and pieces up and hoping to start construction next weekend. I'm giving myself a few months to get this done, since I'll only be able to dedicated 5-10 hours each weekend and very few weeknight evenings.

Oh, and thanks to everyone for the hours of entertainment as I crawled through this forum and read through the last few years.

Welcome!

Michael!

4) Can anyone see any downsides to using composite materials for making the foils?

Technically the timber foils are composite ;-) Its just that your core material is wood rather than foam. You could potentially use a timber 'spar' and use foam leading and trailing edges, but I suspect they would be nowhere near as durable.

yes .. that is the point. Even professional foilmakers in Australia will usually use timber cores because the foils can be so durable and easy to repair. Also they do tend to damage in ways that are easy to fix. Usually slight trailing edge damage only even with considerable impacts!

Best wishes
Michael