Few days ago i had a good swim with added delight of keeping a sinking rig afloat (failed :) ) in good breakers. Board long gone after the below: nut of the base bolt cleanly ripped through the mastbox. Similar damage on both box sides, clearly the contour of the nut simply removed clean chunks of plastic . Base is a Nautic Jumbo, good stable base. Board is HD, carbondyneema chi-chi-cha-cha. Rinse was very ordinary short period windswell and well managed. Box is likely Chinook.
Never even considered this happening? Anyone else?

Yes saw it here. Two bolt help spread the load plus there's no damage to top of the board from repetitive screwing on when using just one bolt.

Route it out, install new one, switch to the two bolt and keep shredding!

Sometimes the nut / plate isn't square. They have long sides and short sides, same as US box fin nuts.

You've got to align them right.

Even if they are square or recessed like the chinook ones to make them slide easier, they can still twist as you tighten them.

It is pretty fiddly poking about with a screw driver and jiggling it all to make sure the nut sits with maximum contact on the plastic and not with the short sides in the slot or diagonally across it.

Like Manuel7 says, a two bolt base that stays in the board is a bit less faffing about and bit more reassuring it won't come loose.

US box fins are the same. I find some fin nuts are just the wrong size for some boxes. The short side is too narrow to have decent contact or the long side too wide to fit in the slot.

Good point on the nut shape!

ffs, any suggestion of my nut not being square/ wrong placed is highly offensive.

20 years+ euro pin, like all here

seems to point to a bad box rather then anything else

I'd also say bad box.

Board construction not relevant. ..... never seen chinook in factory boards from Cobra but you're hinting its Witchcraft?
Thus, could be a Chinook track if so

Anyway, i wouldn't get angry - as with any injrction moulded product there could be a void in the plastic, and if anything is a great test its wavesailing. Stuff happens in waves

it's a custom, but not Witchcraft. Box is sourced by the shaper, and duly embedded. Keen to learn if it is a Chinook or else...it's a rare defect but there seem to have been some other cases, tbc..
Not angry, just banter btw ??
Anyways, wil have this out and replaced as soon as i find a good sandwichmaker.

Cool cool
Most likely chinook i guess but there are chinese copy things, identifiable pre-install, but hard afterwards
I hope a custom guy is not using the no brand stuff....it's usually same mould but low quality plastic with no fibre etc

Never seen this happen with a mast track or chinook...... only with brittle longboard boxes used as foil tracks by idiots or companies that dont care

thanks for confirming my suspicion there are copycat boxes out there. The brittleness of the material is something of a giveaway. ( i held&kept holding the mast, in feel; no brutish rinse at all)

thanks for confirming my suspicion there are copycat boxes out there. The brittleness of the material is something of a giveaway. ( i held&kept holding the mast, in feel; no brutish rinse at all)

thanks for confirming my suspicion there are copycat boxes out there. The brittleness of the material is something of a giveaway. ( i held&kept holding the mast, in feel; no brutish rinse at all)

thanks for confirming my suspicion there are copycat boxes out there. The brittleness of the material is something of a giveaway. ( i held&kept holding the mast, in feel; no brutish rinse at all)

Is there a problem with Chinook boxes ?
I use them and have never had a problem. I'm regularly using a PB with a 55 cm pointer and I'm heavy . I thought their fin boxes to be particularly strong because they are long enough to go through the board , stopping them rolling . They seem solid and chunky , if anything on the heavy side. The mast tracks seem solid and not brittle. I'm sure they are glass filled plastic .
Should I be worried
I have also wondered about those cheap Chinese ones on Ebay.
As an ex injection moulder, there are plenty of plastics that can be used . Everything comes down to a price . Regrinding rejects and remelting back into new parts is not good . Recycled plastic is even worse . When you re melt plastic it loses a lot of its properties and becomes more brittle . The Chinese stuff is probably made from the cheapest , nastiest recycled crap .
If underpacked , thick plastic products can contain air bubbles , but that is just bad moulding . A bigger problem , and this could be the case above is , getting the part out of the mould too quickly before it has solidified enough. Time is money . As a guess , with the thick cross sections in a mast box , a minute or more of cooling time is needed in the cycle , which is a long time . ( the cooling time for a water cooler cup is about half a second ).Premature parts can then warp and twist when cooling.
I'd bet the mast slot gap is wider than it should be for that to happen . You definitely shouldn't have to square up the T nut when tightening the mast base. Something is wrong.

ive ripped a box out speed sailing. got lifted by a gust, board turned 90deg to direction of travel and rolled pulling the box out.

it can happen.

I suppose if you crash hard enough or get dumped , something has to give.
You read about the guys doing crazy stuff in massive waves , regularly break stuff.

Check the length of the box... it looks short. If it is not 8" or 10" it is not Chinook... Chinook boxes are made from glass filled Polycarbonate.

Thx, indeed, it is a shorty. And nasty brittleness seems to indicate no fiber content..

the reason i bang on about this is safety. In winter the juice goes down to 6 deg Celsius here with nice current, hypothermia is swift and kind of blissful ;)

Quote: "ffs, any suggestion of my nut not being square/ wrong placed is highly offensive."


I lolled : )

Select to expand quote

Doggerland said..
Thx, indeed, it is a shorty. And nasty brittleness seems to indicate no fiber content..

the reason i bang on about this is safety. In winter the juice goes down to 6 deg Celsius here with nice current, hypothermia is swift and kind of blissful ;)

im wondering if its a structural failure and not a box failure. have you talked to the shaper?

could be lots of things. like just bad luck,

or no high density foam around box or not enough, could be no extra cloth when mounting box or just not enough layers of cloth in that area. could even be the wrong resin mix used ie filler rather than structural. could be the box too. so hard to know.

was the board built extra light or heavy.

This was mine last year at Fangys. Tripped a rail and leavered out the base. Most of the damage was done dragging the T Nut through the mast track. Mast track still solid thanks to James's build quality. Just rebuilt the bits that were missing on the track and re glued the deck down.

a nice Carbonita!
Thx, similar, a whole lot more of box gone though :))

Off to the repair artisan/local shaper, maybe he'll route it out live for the old kid

So, the board will get a Chinook mast rail fitted.
I fumbled it intensively, admiring its greyish fibrous qualities and inherent promise of flawless tabletop-forward execution.
Will be forking out 300 euros...

Forensics: the original builder meanwhile admitted having had a run with 3D-printed mast rails. In-house. Later abandoned because of "problems of repeatability"...

I am flabbergasted in more then a few directions of thought..

May this -for once and forever- remove any lingering doubts about the squareness of my nut.
Kind regards

3D printed plastic That has got to be the weakest way of making something from plastic. What was he thinking ? If you hit it with a hammer , it will explode . That should be a safety recall. Is the finbox the same , footplugs ? Hope your a good swimmer .

^^^ agreed

I would not fork out any euros to anyone who thinks they can 3D print a mast track.

That's such a poor idea, any custom board builder should know that..... and I'd demand a Chinook track installed for free as his ****ty experiment to save 20 euros failed.

BTW, 300E for just replacing a track is bloody steep anyway!

It is, especially for someone working with composites...
Bloody liability, scale of it..don't know

It is steep indeed, but i don't have umpteen options here.
Was offered a replacement box by mail *vafanculo icon*

If your handy with tools and you can get your hands on a router , we could talk you through the fix.

and here i was thinking the guy was above board because he was open about trying 3d printing.

yeah, appreciated that. Good shapes, good constructions, fittings...except this one. It happens. For a reason. And he was straightforward about it after he could check the build series.
So no naming/shaming from me for poutypouty's sake.
Routing etc, thanks. used to but just don't have the place and time anymore, became a gullible consumer of services left&right :)

Select to expand quote

Gestalt said..
and here i was thinking the guy was above board because he was open about trying 3d printing.

Yeah the honesty is nice.... but still the honesty was after it failed and customer asked..... If his experiment didn't work, would be nice to contact customers and advise..... cos custom stuff, its not Cobra...

Then to charge for replacement of a $30 part and so replacement is pretty much all labour cost

Gobsmacked.

Nah fk it, now I will spout off a bit...... my boards get the first customer-caused ding repair for free. I mean I've still got the cloth offcuts and paint can sitting there, so why not, right?
500 dollars for a mast track replacement is insane.
Further it is the board-makers fault for trying 3D printing that clearly will not work when its about 30% the strength of injection moulded GRP that has been used for decades.
Trying to save a buck on a $30 part then charge $500 to replace? I seriously hope the guy who built the board is not charging $500 to replace his screw up?
Wow.

If you were in WA, I'd do the job for free even though its not my fault, cos I know a happy customer is loyal later.