timberwolf

[Guest]

Now reading that put a smile on my face - good one Tim.

[Guest]

what an awesome day sunday was! beat repeat offender by 41 minutes in a 5 1/2hr race, and we didnt break anything. i was suprised at how easy the wolf is to sail 2 handed and when you want to do something, you can just walk away from the helm and it keeps tracking straight as an arrow. now i can sea why AA has converted to a multihuller. thanks again tim

[Atom Ant 0]

There's a glimmer of hope for you yet Jordan - but wait, you're joining the Army right? Oh well, enjoy it while it lasts

 

Yes TW looked good yesterday and certainly marched away from the fleet after a bloody good start.

[Mothership 6]

TIm, we saw you going past on Wednesday, very much on a lean. Sorry didn't get any decent pics, as was too busy watching the show!

[TimW 1]

what an awesome day sunday was! beat repeat offender by 41 minutes in a 5 1/2hr race, and we didnt break anything. i was suprised at how easy the wolf is to sail 2 handed and when you want to do something, you can just walk away from the helm and it keeps tracking straight as an arrow. now i can sea why AA has converted to a multihuller. thanks again tim

 

 

Actually Jordan is very good on the boat. He would keep the boat tracking nicely when he's on the helm and quickly got the jist of tacking and gybing.

 

Enthusiasm can take you a long way !

 

That is a great course we did as well. It wouldn't matter which way the breeze is blowing its always going to be interesting.

I think its a shame there weren't a few more boats out to play especially two notably absent trimarans.

[Guest]

Great day out, Thank you Tim for coming all the way Up to Play with the fastest Nine Meter Trimaran in NZ.

I was a bit Miffed at the Time difference but then I stared to think back a couple of years and you would have done the same to me then.

So then of thought of all the improvements you have done and I thought, We did okay for a couple of old farts in a Heavy old "Cruising Tri"

 

Fantastic day, once again thanks for coming Tw.

[bushman 12]

More like a couple of old bastards ...... but sounds like you all had a good time.... do you still remember it offender

[Guest]

Remember what Offender? what you talkin about bushman.

 

Ah I remember now, you were telling me the other day, "the only problem i have now that i'm old is not forgetting to do up my fly, It's forgetting to undo it"

 

Never mind old fella age does tend to catch you out from time to time

[TimW 1]

 

Here's a couple of nice shots taken by Rob Webb from Phil Hart's plane.

 

Just before this we were cruising at 27 knots, still not 30 but nevertheless pretty fast for a small tri.

 

The waves don't show up in the photos but they still needed respect and at high speed when the foils let go over a wave it can slow down pretty quickly.

We soon found a safer speed was between 21 and 23 knots especially in the shorter waves (the longer swells are less of a problem.

[rigger 47]

Looks Great

[MartinRF 53]

Looks Great

I agree and I am very envious. My boat is on the hard and covered for winter -- no sailing until May next year.

 

/Martin

[Atom Ant 0]

Come over here Martin, I'm sure you'll be able to hitch a ride on a raft somewhere!

[TimW 1]

 

Here is the Blank for the new Centreboard.

 

Started by Laying Up the Carbon , on which a Cedar Stringer forms the centre with 130 kg density foam either side.

 

This is the machined by Styrotech to the same section as the Old board to make sure it fits in the same case.

 

Thank you so much to Russell (of Absolute CNC) for Modelling the blank so that Styrotech could machine it !

 

The new board has a little more laminate than the Old one, with a Much Higher density core (up from 80 kg).

 

But the main change will be that it will be tied in so the top of the board can't fall down too low in the case.

[Guest]

[attachment=1]DSC07797.JPG[/attachment][attachment=0]DSC07798.JPG[/attachment]

 

Here is the Blank for the new Centreboard.

 

Started by Laying Up the Carbon , on which a Cedar Stringer forms the centre with 130 kg density foam either side.

 

This is the machined by Styrotech to the same section as the Old board to make sure it fits in the same case.

 

Thank you so much to Russell (of Absolute CNC) for Modelling the blank so that Styrotech could machine it !

 

The new board has a little more laminate than the Old one, with a Much Higher density core (up from 80 kg).

 

But the main change will be that it will be tied in so the top of the board can't fall down too low in the case.

 

 

Tim - Is that why the board/boards? broke - cause they fell-down/out to much & just - twisted off due to the loading?

 

Even at 130/kg/cu/mt - high-density foam doesn't have much going for it - when talking about the physical factors governing c/b & rudders. ?? IMHO

 

Much is to be gained be the choice of the correct foil - in all dimesions - as you already know - especially reducing the breaking strain on the foil while reducing drag & increasing lift both to windward & up. ie; Drifting aft of the max cord as a % of the foil length - fore & aft. Again - Questions here & IMHO. So everyone else in here doesn't think I'm being rude to Tim - I do know that he's - out-in-front - of the leading edge of all these development matters. I do have a little bit of knowledge about some of these things & thought we might all learn more if it was discussed in open forums, up to a point. I'll bugger off - if people think it's not important. Ciao, james

[TimW 1]

The section we use on both Centreboard and Rudder is NACA 63014. It is a laminar flow section ideally suited to a High Speed Trimaran.

 

The Core Density is very important as the two most likely modes of failure in a foil are in Buckling, either outward buckling caused by Core Sheer Failure (very common in Centreboards) or Inwards buckling, alleviated greatly by a Higher Density Core.

 

The Core sheer properties are most governed by the choice of Foam, in our case a Structural Airex PVC core.

 

While the Carbon Laminate (5mm thick where it exits the boat) does most of the work (in compression and tension) the Core has a vital role to play.

 

Our rudder that broke failed because the core compressed.

[Guest]

HI Guys and girls. Cool looking board Tim.

IS there a way Offender could have a new lighter slimmer foil without ripping out the old case?

The old board weighs about thirty five kg dry and has taken on water, I think it is solid timber.

 

Rudder is an easier option it weighs a ton as well.

[MartinRF 53]

My English fails me when I try to read Silver Raven's post. What's it saying? (English is not my first language)

 

Tim: I would think the timber spar is up to all shear and cross-grain compression you throw at it. My rudders and my first set of dagger boards had nothing but air in them apart from the wooden spars. No buckling ever observed. My present boards have 50 kg foam apart from the redwood spar. Those boards have been with me since 1995. Uni carbon on the spar, stitched +/- 45 glass cloth wrapped around foam and spar.

 

Those NACA foil sections were designed for far more ideal flow than they see under a small boat sailing in waves. You are probably quite OK anyway since you stayed away from the thinner sections. I use ca. 13% for my dagger boards. The section was designed to be more forgiving to non-ideal flow situations.

 

offender: A thinner board in the old case should be no problem. You would have to re-shape the lower exit to avoid turbulence. This is what I did in 1995. I used home-mixed graphite-epoxy putty.

 

/Martin (who wouldn't mind visiting NZ some time, should improve my sailing...)

[TimW 1]

The curved foils lift the boat up out of the water and when it lands again it comes down sideways, as in a lot of leeway.

i think that that is where the extra load that the foils must be seeing is coming from.

As the foils that have broken, 1 cb and 1 rudder have been on the boat for over 5 seasons.

 

The foil section we use on the cb, Pedro is 425mm fore/aft and 60mm thick.

It weighs around 20 kg and it is not an area I am going to try to save weight in.

 

Foil design is complicated, and the 63014 section we use is a nice all round section with a forgiving angle of attack that combines quite low drag properties at speed but hardly ever lets go (stalls) at lower speeds.

Have been using this section for years on both skiffs and the tri.

[Hurts 6]

I have to build a couple of centerboards for my project - I'm kind of putting it off till last job - I don't have much choice on profile as I really just have to follow the shape of the existing case but interested to know how you went about the process for yours. Is the basic process this:

 

1: Get those foam cedar core halves CNC'd (very nice looking BTW) ,

2: glue them together

3: Run crap loads of Carbon Uni down each side

4. wrap crap loads of carbon DB around the outside

5. Bog, fair and paint

 

That is kind of my understanding of how you can do it. Otherwise if you have mostly straight sided boards you could invest the time in building a female mold and build outside-in but I'm a little hazy on that exact process - seems like you will get better control of the final shape and do less bogging and fairing. Interested in your thoughts on pros and cons.

 

For the CC how many foils/boards did you break (and which ones).

 

Edit: OK looking and reading again - you actually have Carbon down the center (I think)- that's a little different again and I'm not sure I understand what the middle carbon might achieve - by having it down the middle, can you avoid having the uni's down the sides? - what sort of cloth have you used in the middle??

[TimW 1]

So we started with a layer of Carbon cloth onto which we glued the Cedar and foam.

 

After it was CNC'd that is the photo you see.

 

where the cedar is there is a rebate, 3.2 mm for the Top 1300mm and tapering to a 2mm rebate at the bottom.

 

This allows us to put 110mm wide Carbon Uni strips that fill the Rebate.

 

The laminating is mostly done in two halves.

 

The Outside of the board is then covered in a further laminate of 1.8mm thickness. It is not DB on the outside but rather is made up of around 65% of the laminate in Unis at zero degrees, 28% in CDB at 45 degrees, and the remainder at 90 degrees.

 

The Central Carbon layer is basically there to form the central part of the trailing edge and to keep the trailing edge sharp and straight for joining purposes.

You will also see there are 3 dowel holes in the board to keep it straight when the two halves are glued (under vacuum) together.

 

After the board is joined there is a DB tape applied down the front only (approx 60mm wide).

 

The board will need very little fairing and I rate it certain to fit in the case !

 

Yes, the process can be done other way round in a Female Mould (as I do with my Rudders).

I never bought a Centreboard Mould so this is the next best option.

Does result in more fairing this way but saves the cost of the mould.

 

The Coastal reports were wrong.

We just broke the Centreboard in the main hull.

It fell down around 150mm lower than usual (it had 150mm more out the bottom and 150mm less in the case) and when we landing after launching off a wave it snapped.

 

We continued to sail after it broke with just the curve foils down but we were going sideways pretty fast, and only making a VMG of around 2-3 knots while tacking through 110-120 degrees.

I decided to withdraw and Motor home because at that stage it seemed pointless continuing (to me) and as the broken piece of board was crashing into the bottom of the boat (it was still attached) I didn't want to risk it puncturing the hull.

Later under motor it eventually broke off and no damage was done.

At no stage were we in any danger at all, however.

 

It was a very disappointing way for our Coastal to end as at times we had been going very well and would have been confident of doing well on the final beat in those conditions.