Morning Julio

As ever, very informative and looking really good. Now to turn over and get that high gloss on the decks :)

Ths may also be of interest

http://airfoiltools.com/airfoil/naca5digit

HI julio, really looking good, cant wait to see you sailing

Julio, may I ask when your (lovely) build is finished, what club will you sail from?

Truly inspirational Julio am tempted to have a go at this myself. Sadly will not have the space until Autumn 2014!

Hi!

I hope everyone is doing well. I just updated my blog and managed not to delete it (again)before publishing it (what a relief!). In January, I applied the final coats of paint to the outside of the hull and primed the foils. Wet sanding wasn't fun but she is looking good.

Cheers!

Julio

Thank you, Rob. It's going to be a lot of fun!

Barnsie, thanks. Indeed, time to get her deck built and give her some curves and gloss!

Hi Chris,

 Thank you. Yes,the centreboard tip is per Keith's specification as shown in the full size drawings and based on the NACA tables he provided. Same as Wicked's. Right now I'm learning so I'm following every shape and dimension per Keith's specifications.

 Once the boat is done and sailing (with me on the boat!), I plan to build new foils and experiment with new  fabrication methods and materials. But there are a few other interesting shapes that can be seen at Pinbax.com and on the Internet. Some of them look really cool but I'd love to understand the science behind it!

Cheers!

Julio

Miles, thank you. Yes, working on her inside and deck is next.

Chris,thanks for sharing the link. Pretty cool video. I like this approach better than the one I followed. I believe it may also resemble the routing process Barnsie described a month ago. Rather than tapering the foil's tip by hand, a similar approach can be followed across the foil using a router sled similar to the one I built to cut the scarf joints.

Cheers,

Julio

Yes, the centreboard achieves maximum thickness at 40%, and the rudder at 30%. Take a look at my November 2013 update, where I describe the steps I followed to achieve the specified thickness at each station and ordinate. Then in December, I tapered the foils below +700mm for the centreboard and below +500 for the rudder. Amazing how much dust and wood shavings came out of such a relatively small area!

My interest in building another set of foils is to learn how to make moulds for composite foils and have at least one extra set on hand when I hit the inevitable underwater obstruction. The improved performance will come in handy once I start racing her.

James, thank you. Autumn 2014 is just around the corner. Good time between now and then to start planning the project.

Chris, thanks for sharing the link to the int505 foil construction. The tolerances are very tight indeed. When you say "if the centreboard case is not immaculate..." are you referring to the bolt alignment? 

Cheers,


Julio

Nice airfoil tool site, Barnsie. Thank you.

Chris, I couldn't agree with you more. I've also learned that when making the foil one must take into consideration the reinforcement materials, the resin and other finishing products that will be added onto the surface so that it fits properly in the centreboard slot. Fortunately, I have a set of drawings from Keith that factors in those requirements.

Julio:

Thank you for the update!

That is an interesting centreboard tip design. I guess I am more used to seeing them end like you have finished the rudder...

Was the tip to Keith specification, just curious?

Amazing build by the way. Thank you for writing it all so clearly and diligently.

Many thanks,

Chris

Julio:

Thank you for the reply, very interesting.

The below looks to be very effective if you are building straight foils.

You Tube: How to build a composite dagger-board:

http://www.youtube.com/watch?v=9KK-3kfX7x8  

Cheers,
Chris

Julio:

For what it is worth, most everything I have read says that the first 0~>30% of the foil is doing the majority of the work and is where the greatest degree of accuracy is required. Do you know if the foil is a laminar section? (max thickness further back, say 40%) I only ask because my understanding is that they need to be built to very exacting standards to get the low drag 'bucket' reduction. Your idea of building a set of foils to get yourself on the water is spot on....the rewards for going 'crazy' re accuracy are diminishing and if you are not racing against a facsimile boat probably irrelevant.

Cheers,

Chris

Julio:

Sounds good.

My reading is that what you have done is within a small % of what can be achieved by hand/eye. Moulds would potentially allow you to achieve an exact specific finished dimension (i.e. that is one reason why the best grad prix boats are made in a female CNC mould).....but to do better you would need to go to CNC�?�I would suggest....

....far better to just go sailing. If you hit something you can refinish the foils you have made very quickly....if you make the genuinely amazing CNC foils i.e. like the very best foiling moth foils, then I would think that restoring the 100% exact edge becomes harder....

...oh yes, and always check your centreboard case....if it is not immaculate then your perfect foil last 5 minutes...
See figure 11 re how exact you need to be in production.
http://www.int505.org/old_site/eck2.pdf 

Cheers,

Chris

She's really looking the part. Now eagerly awaiting the turn over.

Julio:

My remark re the centreboard case was born out of my limited experience of carefully preparing a board and then being disappointed when i removed it and found that its surface had been damaged by an imperfect case.

My conclusion was that the case needs to itself be clean and free from scratches that can retain grit that damage the board when it is moved up/down. One solution is to make the width of the board head ~equal to the case and then the aerofoil surface itself ~1mm less so that the prepared surface of the board does not touch the case etc etc.

Just a thought.

Chris

Hello Ben,

I have a couple of options close to where I live. The Austin Yacht Club or the Lake Canyon Yacht Club are suitable candidates. However, I may join the Texas Centreboard Circuit first. The TCC is designed to give all Portsmouth Centerboard Dinghy Classes, that don't have active fleets, a chance to participate in a series of races throughout 9+ yacht clubs in Texas. This will allow me to meet the members, take a look at their facilities and decide which one to join.

But first, I must finish my build. I'll have the February update in a couple of days with lots of pictures and comments.

I got up early to work on the boat,

I hear the coffee pot beep,

so off to the garage I go,

while everyone else is asleep,

fair winds to you and all!


Cheers,


Julio