Micro Class International

Helge · Posted: 04 Jun 2007 9:08 Post subject: Gennaker on microclass

Is there any max length on bowsprit?
Is it allowed to have it pivoting or does it have to be in a fixed position?
Is it allowed to use a gennaker on the spinnaker bom? Max length?

Phil De Troy · Posted: 04 Jun 2007 18:54 Post subject:

Sail area is the same as for a conventional spinnaker, just substitute Leech Length by average of leech and luff length.

Bowsprit may be oriented

Max extension of bowsprit is 2/3 foot length (2,80 for Foot Length 4,20)

If spinnaker boom instead of bowsprit, limited to 2,25

Is half width less than 75% foot length, use 75% foot length instead of mid width for calculation...

Please keep me informed of the results of your tests.
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Helge · Posted: 05 Jun 2007 9:20 Post subject: Mast halyard point

Thankyou, that gives (theoretically) a possibillity to get free wind for the sail, but it is very difficult to have a support line going from waterline-level to the tip of the bowsprit. This system which is used by the minitransats does not work because the bow is not vertical. I tried this system on the Ricochet, but had to leave it. A possible solution is to move the forestay and the pole attachement back 25cm on deck, to get better angles when orientating the bowsprit. Else it will just twist out on the sides.

An unstayed bowsprit takes a lot of force.

Is it allowed to use 2 spi - poles at the same time(with 2 tacklines)?

Halyard point attachment on the mast - the same as spi?

Phil De Troy · Posted: 05 Jun 2007 9:30 Post subject:

Halyard: no more than 20 cm above headsail halyard.

A self-sustaining bowsprit may extend 60 cm out of the bow, and have the inboard end in front of the roof. A long transversal support plate spreads the load on a wide area.

A warning: when the gennaker is not in use, the bowsprit should be retracted within the limits of the template (see Part 4 figure1)
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Helge · Posted: 05 Jun 2007 9:48 Post subject: 60cm??

So if the bowsprit has a little line of support it can be longer? 60cm is not very interesting to compete with. In the LYS (Lidingoe Yard Stick)they allow J x 0.33 = ca.60cm. Any comments? I have tried this messure and the gennaker works better with more free air. I am now working on my third system of bowsprit which is 110cm, fixed and retractibile. (microclass.no)

Phil De Troy · Posted: 05 Jun 2007 14:03 Post subject: Re: 60cm??

Longer self-supporting bowsprit becomes heavy.
According to our formulas, the absolute limit with average SL 6,40 is a spinnaker foot 4,59, hence a bowsprit extension 3,06 and a half width 3,45 or so.
Most of the gennakers have a half width much more than 75% foot, so usually the bowsprit may not be so long.

Taking the forestay back is dangerous, as there is no strong structure to hold it at that place, and the boat could become very hard on the helm
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Helge · Posted: 05 Jun 2007 22:17 Post subject: bowsprit

An ideal bowsprit would be an orientable one, 1.5m long. Have anyone made a such one?

Helge · Posted: 06 Jun 2007 9:29 Post subject: Gennaker pole

Would this "stayed" pole be allowed?

Phil De Troy · Posted: 06 Jun 2007 9:44 Post subject:

No problem, except that for racing in the Micro Class the pole should be retractable. You need place on deck, and it's best to retrieve the line too.

I've seen some good systems with an inox tube and eyes on both sides, the pole passing through, the system fixed between forestay fitting and the forestay. A block on the inner end on the low side, just a smoothed plastic end outside with a tack line passing through the pole to the block at the inner end, than another block at the forestay fitting and back to the cockpit. When you are setting the gennaker tack, the pole goes out. Then a strong sandow brings the pole back when the gennaker is lowered.
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toni · ** Joined: 09 Apr 2005 Posts: 10 Location: Germany

hi to all
i made a bowsprit out of 2 surfmasts.
the outer part, fitted to the boat, is quite stiff, carbon-inforced; the inner part (green) just fitted perfectly inside but bends to the side going upwind.
it is really light and easy to fit; i found a good construction by lucky chance: the rope doesn't hold the bowsprit but just blocks it (see fotos).
the sailarea is 25m2 and the halyard 45cm above the headsail, so it is out of the rules anyway.
extended, the bowsprit moves out 125cm.
upwind it works well up to 2,5bft, going up to 6 knots boatspeed, perfectly balanced on the rudder.
downwind i used it so far up to 4 bft, up to 7 knots, still not planning and producing a rather big wave.
this weekend on the baltic sea we came out of between two islands, 2 bft wind in our back, when we were suddenly hit by 4-5 bft from the side in a still narrow water and it was not possible to handle the sail/boat anymore, we just had to get the sail down - the power produced by this sail was really impressing - and fortunately nothing broke.

Jorge · * Joined: 03 Jan 2007 Posts: 5 Location: Argentina

Hi all,

Here is a Micro with bowsprit racing under PHRF in about 20 knots in Rio de la Plata (River Plate), Argentina.

I don't have much details about the sail area and how the bowsprit has been setup but will try to get information to share with you.

Jorge

PD: if you can't see the picture, please try at: http://gustavoal.multiply.com/photos/photo/9/3
sorry but I don't know how to post pictures on the forum...
*** problem was corrected by the Forum Manager, URL's of pictures must have a recognised file extension .jpg, .gif or .gif ***

Argentino · - Joined: 14 Aug 2008 Posts: 1 Location: Argentina

Hola, mi nombre es Franco, soy de la ciudad de Buenos Aires-Argentina.

Mi barco es un Micro Volker reformado, con spinaker asimetrico y botalon.

Env?o una foto.

toni · ** Joined: 09 Apr 2005 Posts: 10 Location: Germany

hi all

finally a photo of my 25m2-asy

Phil De Troy · Posted: 21 Sep 2008 13:34 Post subject:

Very nice indeed

However, in the present state of the Class Rules, this sail should be illegal for racing, not only because the area is over the limit, but also because the spinnaker halyard is too high (approximately 7 meter instead of 6,54 as the standard height of the headsail halyard is 6,34.

Can you give us the measurement information, it is:
SLu (luff length)
SLe (leech length)
SMG (mid width - measured between the mid points of luff and leech)
SF (foot length)
STW (spinnaker tack length- from the fore side ofthe mast to the end of he bowsprit)

In addition, this is not a requirement of the present Class rules, I'd like to know the median height SMH, from the mid point of the foot to the head point

if you want to race at national level, as Germany is sailing national events on handicap, the oversized spinnaker may be allowed with a penalty on yardstick.
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toni · ** Joined: 09 Apr 2005 Posts: 10 Location: Germany

SLu (luff length) 823cm
SF (foot length) 430cm
STW (spinnaker tack length) 303cm
the rest later ...