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NACRA Infusion Poor performance


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Hey All.

I have an Infusion and love it right up until I tack onto STBD

Once on STBD Tack I get overtaken by Hobie 16's. They sail higher and faster than me.

I liken the performance to sailing with a ton of weed on the centerboards.

I have done heaps of Fault finding and I have come up with nothing that would make a significant difference. I have had 3 different people sail the boat all agreeing with me on the performance but no-one has an idea what it is.


I can reduce the poor performance by rotating the mast to the downwind position. It doesnt seem to be very bad when its light and seems to be worse at 15-18kts

On Port tack it is rocketship fast almost as quick as the Tornado's and make all other F18's in my vicinity look like they are stopped.


I have had heaps of people look it over and no-one can see anything that would make that kind of difference.

I mean the sidestays would have be a foot longer to make a difference or the diamonds be 6 inches longer on one side but everything measures within 5mm and I have adjusted them to be within 1mm.


The only thing I can see it is is the mast looks like it is twisting along its length. Hard to see whilst on the wire and everything goes back to perfect once all the load is taken off the boat. But I think it is twisting the same way under load.


It seems a little less responsive on the opposite tack with the kite up but not significant enough to think the problem is related.


I have put up a full brand new set of Rags on the weekend and the problem seemed to be exagerated more with the new sails.


Please help or point me towards regattas where I only need port tack.



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So, on port your stbd hull is out of the water (or close to it), on stbd it becomes the main weight bearing component.  Have you weighed it separately?


Have you put a post on sailinganarchy - there'll be a worldwide infusion audience there.  The problem may have occurred somewhere else.


Are the foils interchangeable or specific to each hull.

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Have you pulled the diamond wires off the mast and checked to see if the section is straight? it may have more tension on one side due to a bend. would also be good to check the diamond wires them selves are the same length as well as the side shrouds are even. 

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Hey People thanks for your help. Thanks Gareth for your words of wisdom My Infusion is slow at the moment but still floggs you haha


Since putting this post up I have done the following.

Checked Diamond tension left to right - all good

Checked sidestays - Within 1mm length

Checked Spreaders - Within 2mm angle spot on for height


Swapped Centerboards left to right - No change

Put a Brand New set of sails on - Marginally worse.


Mast is dead straight.


1 thing to note is the lower the wind the less the problem. Also note that I get some of the performance back if I set the mast rotation on STBD Tack to the downwind position.


Hard to tell from the wire but it looks like the mast is twisting the same way both tacks.


I have just taken delivery of a new set of spreaders, Rod ones as opposed to the wing or Proctor type.

I will give this a go tomorrow and if not One of my mate will lend me his mast for a day and see if the problem shifts to his boat

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Don't take this the wrong way, but have a swapped out the skipper and how right handed are you?  On Starboard tack you're steering with your left hand.


Going through and swapping out components should help you narrow down the problem.  The idea above about making sure the two hulls are the same weight is a good one too.  hand the boat by the dolphin striker and back beam and see if it balances.

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Had this issue before..... mine turned out to be a 'stretching' shroud




did you measure the shrouds and diamond wires slack or tight ??

Its makes a huge difference if you rig the boat and then load it up and THEN take your measurements.....

I'd also take measurements to a set point other than the chainplates aswell -> measure fully rigged and use the beams aswell for your measurements, this can assist in finding an unseen hull twist


have you replaced any of the wires or does one look slightly newer ?

a single shroud or diamond wire replacement may well be interfering with the balance......

its like wearing one new shoe and an old boot ;)


did you slacken off or remove the diamond wires to check the mast straightness ???

the diamonds will 'hold' it straight while the mast is laying on the trailer etc.... loaded up (rigged) it may well be showing up a soft spot.

I'd also be checking how straight the mast is as you rotate the mast...

the hint here is from your own words ->  I get some of the performance back if I set the mast rotation on STBD Tack to the downwind position.




My next step if I were in your position.....and your satisfied with the wire lengths....... is to borrow a mast


I get the feeling that at some stage the mast has been dropped and put a slight kink in it, that kink or softened spot may only show up under certain conditions and subsequently cause the confusion your experiencing....




A simple test that may also help in a big way would be to fit a go-pro camera to the masthead with the camera looking straight down the mast, when I did this I was shocked at what I saw happening to that old stick as I sailed through the various angles of wind


swap the port shroud to the stb side and vice versa, swap the diamond wires too, if its wire related then the poor sailing should now be on the opposite side

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A little trick for checking your mast for bends.


After removing spreaders (not done in the example) take a photo down the length of the mast (take a couple so you can pick the best one).  Put it in photoshop and reduce the image height.  Any bend will quickly become apparent.



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Thanks heaps for the advise.

I do run pretty high rig tension and have done my measurements with the rig tension on and I measured to a point on the boat rather than the stay length.

But for it to be a stay it must be stretching a foot as small deviations dont really make too much difference. 

I did slacken the diamond wires off and checked the mast and it looks pretty good I cant fault it even the smallest amount. I have re-tensioned the diamonds still all good.

I have swapped out the skipper and I have had 3 different crews. All much the same although it was light when I swapped Skippers.

I am right handed but it is rare for me to have the main sheet and usually when I have it, its light and the problem is not there in light conditions.

I feel that the mast may be twisting and I think the go-pro is an awesome idea.

I have bought a new set of Rod spreaders and I am ditching the wing ones as I know they are not matched. They are the same but the boat was missing one when I bought it!!

I have a bloke on Standby with a new mast and he is going to lend it to me.

One observation from ashore is that my mast bends significantly under kite and I run my mainsheet in slightly cracked position with kite up. For people to comment ashore it must be significant.


Will change out the spreaders and see if I can borrow a go-pro or ask Santa to deliver early. I really need this sorted before the F18 nats or my trip from WA will be pointless.


How is the mast constructed it there a possibility of an internal failure?


Have spoken to NACRA and I think they think I am after warranty but I am just after an outcome.

It is quite possible that I have broke it if that is what the problem is.

I sold my Tiger for a better performing boat and I now have Tigers whoopping me. I wonder where my old boat is....

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interesting comment on the spreader, it may well be the cause or part of your issues :cool:


The "GoPro" idea is a good trick and will help sort / solve a supprising number of issues, its just a fantastic tool that we have these days and no-one should be without one in my opinion....... having said that.... the "GoPro" it self is really the term we use for an ultra small video camera.....

I have a Aldi elcheapo unit that does EVERYTING that the higher priced units do and it does it just aswell if not better in some instances.... my Aldi unit cost a woopping $45, I also have one that was on special from COLES supermarkets, it cost a massive $39:95 and works quite well although not as good as the Aldi job in resolution, once you move it more than ~5metres away from your desired focal point it looses clarity quite quickly.


Tip for the "GoPro unit you beg/borrow/steal/ or con Santa into giving you (& only if you've been good) ;).... use a short length of venetian blind cord as a "safety rope", I cant count the number of times its been washed off by a huge wave that crashes over the boat, or that small sapling that swipes it off the side of the rally car at gross knots ...... that little bit of cord means it STAYS attached to the boat or car and can be recovered & re-attached later on...... I've seen a few guys in tears over the loss of their GoPros, apparently they don't float that well....





alloy mast construction is like this ....


I'm sure you get the idea now ;)


interesting document, well worth the read if you haven't already :)


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Hey Bevo,

Have a look at your jib car location on the self tacker on each tack. Do you run it all the way to the end? Or do you set it?


The factory fitted jam cleat that is located on the spinnaker pole is often not centered once you tension the rope that runs from the spinnaker hoop to the bridal.

I've had similar issues on the old mans boat, you set the jib car on one tack but because the cleat is not centered the car is able to travel further or shorter on the other tack. With such little jibs the slot can close up forcing you to over rotate and foot off.

I'd suggest letting the jib travel all the way to the ends and see if the problem is still their. 

Try and eliminate one thing at a time you will find the problem eventually. 



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Everyone has their own style and opinion but generally its a set and forget item as you say.


Most of the guys will bring the car up an inch or two in light weather, but most run it almost to the end once double trapping.


I know when I skippered the infusion it was harder to keep the boat in the groove the further up you brought it and the advantage if any was minimal. Then you had the added problem of the cam cleat not being centered, so unless your at the pointy end of the fleet I'd let it out to the end in almost all conditions and focus on boat handling. One bad tack will negate any advantage you get from adjusting it. 

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  • 2 weeks later...

Ok Thanks Everyone for their input.


Looks like the spreaders fixed it. I put them on and it immediately showed an improvement but in my rush I forgot to measure the diamond tension and sailed with it at about 32 which I think is a little light on.

So the next weekend I cranked it up to 42 and the boat is now quick.

The port starboard thing has gone.

So the Fault was 1 spreader bending under load causing the mast to twist on Starboard Tack. It would have been twisting a certain amount on Port which actually made it super quick on port hence exaggerating the problem.

I have raced 5 races with it now and 4 wins so we can put this one to bed.

Thanks Gary Gornall at Goose Marine for your help.

See you all at the F18's

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