Thread: Sydney Oz Racer

That's great!

That means Two boats in Sydney!

Did I tell you there needs to be a temporary spaced held by a single screw in the back of the centrecase?

Nice to have an MG sailor in a OzRacer too!

Mik

No is it mentioned in the instructions? if so, what page i'll have a look as I must have missed it.

Whats the function of the spacer?

Tim

There is some extra length in the centrecase and the spacer takes it to the front of the case.
It is the height of the case, between 19 and about 24mm so slightly loose on the case. Just leaves about 6mm of fire and after slop. Hold in place with a single screw through the side of the case near the top.

Ah, ok. I did notice that. I have not shaped my foils yet, but my blanks are 295mm. I can probably get away with keeping them this width rather than planing them down to 280mm as specified.

I actually have a Flying Ant rudder shaped by Larry Selby which I was going to use. I just need to sort out the centerboard.

Howdy,

In absolute racing terms I would be inclined to take some widths off the foils rather than add any, but it won't make a whisper of difference to the way the boat feels or acts on the water.

MIK

Ok, a long awaited update. The hull is now finished and fitted out. It looks pretty good if I do say so myself. I have departed from the plans in the fit out in a few places and adopted some of the 'go-fast' ideas from my racing days.

I don't really like the idea of the lug and sprit rigs, so I have decided to go for a high aspect main using a cut down old genoa which was under my parents house ( an old Mylar relic from the days we had an Endeavour 26). For simplicity I have made a pocket luff, which as can be seen in the picture below will need to be recut to fit the mast curve.

I have some new mylar and dacron and plan to make a new sail once I know that this design works ok. I am also toying with the idea of staying the mast and adding a bowsprit and asymmetrical kite for a bit of fun.

http://i.imgur.com/qXTsa.jpg
http://i.imgur.com/YoRZF.jpg
http://i.imgur.com/SUsAW.jpg
http://i.imgur.com/dRdx3.jpg

Fingers crossed I will be on the water in a couple of weeks!

Tim

I finally launched yesterday afternoon. Boat works well except there were a few issues. The unstayed mast doesn't go to well with the high aspect sail, Every time a gust hit the hull rig depowered. I am going to make a new sprit sail to see me through.

Eventually I will make a stayed rotating mast so I can fly a spinnaker.

I also managed to snap my tiller during a test capsize. I'll make an aluminium one to replace the Oregon one. The timber split along the grain.

First impressions are that Oz Racers are slow, but fun. I was surprised with how sensitive it was to body position so this is something I will have to get used to.

Looking forward to racing Alex N soon.

Tim

ps. My wife forgot to take any photos. I'll take some of the boats next outing.

Ok, a few things to fix up before I 'officially' name and launch the boat. I have repaired the tiller and started making the new sprit and have measured out the sailcloth for the new sail. Taking a leaf out of AlexN's book here comes a photo essay.

Here is the old tiller that just didn't cut the mustard strength wise;


Which got replaced with this tidy aluminium number;


Which is now firmly attached to the rudder cassette;


Those with a keen eye who are familiar with the OzRacer will notice that I have shortened the tiller a little as its too long when built to spec. with respect to body position when sailing.

I also bought some 40mm radiata pine from the big green box for the new sprit.


As I need to make a 3.6m spar, these two bits needed to be scarfed at a 6:1 joint. I used a little bit of carbon fiber I had to stiffen it up, but only because I had it on hand.


This proved to be very strong. So strong in fact that I broke the new spar through the wood rather than the joint trying to walk up it to test its strength (as Mik does in the OzRacer plans). I have managed to salvage the spar by another scarf joint, but I didn't get a photo of that though. I'll update on the spar at another time.

I am also sorting out the bits and pieces to make the spritsail. My mast is a little longer than specified in the plans so I have recalculated the sail plan for a 5m luff whilst keeping the angle of the tack the same so the COE doesn't change. Some clever triganometry and my old mate Pythagoras helped me out a little bit, but I am looking at a 94sq ft sail. I have some 4oz dacron which is unfortunately in a number of colours so my sail will look either like a Hobie Cat's multicoloured affair or a pride flag. I think both will look pretty cool. This is the sailcloth;


I'll save the white cloth and the mylar laminate for my next build which I am hoping to be a high performance 12ft design. I have hopes that the 'wooden laser' concept gets up, although Mik has posted some lines drawings and I am more than happy to be the guinea pig and make a proto from these lines if official plans are not released before I get the itch to build another boat.

I'll post some more pictures of the remaining elements over the next couple of weeks before my anticipated Australia Day official launching.

Tim

A quick thread to document some boom work I did over the weekend. As mentioned I snapped the boom testing out the strength of the scarf and had to scarf again. I had never scarfed before so I think I have come up to speed rather quickly.

This is the original scarf which has now been cleaned up with the belt sander, its at the end of the boom now.


Here is the other scarf I had to do to rescue the boom.


Here is the whole length of the boom which has been briefly cleaned up. In the plans MIK specified tapering the ends to save weight, but as I want to get on the water sooner rather than later and also because I am using Radiata Pine which doesn't seem as strong as the specified Doug Fir, I'm not going to bother.


I then radiused the corners and ends with the router. Probably no noticeable difference in this shot though! This is the other side of the boom which shows the carbon fiber I used to reinforce the original scarf.


I then moved into my shed for a quick coat of Bote-Cote epoxy. I used the non-yellowing hardener. I also taped the ends with fiberglass to prevent the wood splitting when I drill my holes through either end. The rough looking bit in the bottom of the photo is where there was a small gap in the epoxy filler. I put some epoxy thickened with sawdust over to fill it in.



I'll leave the boom till tomorrow evening and give it a light sand, drill the holes in the ends and then hit it with another coat of epoxy. I'll then give it another sand and coat with marine varnish to finish it off later in the week. I'll then move onto sewing the sail next Saturday morning.

Tim

Just a quick question to the sail making gurus out there. I am going to make a sprit boomed sail out of dacron. As dacron is not as stretchy as polytarp, will having rounded luff and foot be enough to force shape into the sail, or will I need to compensate with cambered broadseams?

Tim

Howdy,

A lugsail seems to work pretty well in conjunction with a loose foot.

A couple of OzRacer sails have been made out of dacron as well as the experimental RAID41 sails and they certainly looked better than OK using the same offsets as I specified for Polytarp.

MIK

Thanks MIK,
I'm going to make the sprit-boomed sail to spec with dacron and see how it goes. Worst case scenario is that I waste $15 worth of dacron.

I've considered the lugsail, but I just want to get this boat working well on the water. The sprit should be a quicker build.

Tim

While I have not done any work on the boom at all in the last week, I have managed to get busy with the sewing machine and make my new sprit boomed sail.

In this photo I have already done and initial lofting and I am joining two boradseams with double sided tape. There is no curvature here as I am making the sail to MIKs plan (less one reinforcing patch along the foot, which I have worked out I won't need using dacron sailcloth).


Here is the completely joined sail that has had the edges trimmed to shape. I am in the process of sticking the tabling down with double sided tape.


And here is a pic with the boom over it for reference. I couldn't get the whole sail in the frame of the pic!


I still need to bash in the islets in the corners and at the reinforced areas every 400 mm up the luff. Overall sewing thsi together was an interesting experience. I just used my sisters domestic machine with polyester thread. It handled 8 layers of 4oz dacron with ease. While the sewing in this sail is in no way a work of art, I have worked out how to handle the machine well enough that I could make another one would indeed look very professional with even stitches etc.

Tim

TIm .... It just looks great!

I dig the colours!

Michael