Nacra Infusion - rear beam plate threads stripped

can-UK

Member
136
44
Dubai
The threads have disintegrated on one socket of the rear beam plates on my Nacra Infusion.

I'm planning on helicoil-ing some new threads in... any tips or warnings i should be aware of?

Has anyone disregarded this and gone for an alternative approach (i.e. larger bolt or a longer bolt with washer and nut)?

thanks in advance.

 

macca

Anarchist
822
10
RWC
helicoil is the best way. the thread is not metric!!! so it can be a mission to find an imperial helicoil in some places.

 
Helicoil or any other recoil-system is the best way to go. When you do so you could easily change to the metric system which will be M10. The aluminum plate inside the hull-beam junction is about 10mm thick. You must carefully check the different types of layers (laminate and aluminum) in order to identify the correct length of the helicoil. As the aluminum used here is soft it is helpful to drill the hole around 0.1 to 0.2mm smaller than recommended. Use alcohol as lubrification during thread cutting!!

Helicoiling looks easy, but as you have no second change to get the bug fixed be aware of it.

greetings from germany

 

can-UK

Member
136
44
Dubai
Ouch how old is your boat? My family owns an Infusion and I definitely don't want that happening to ours!
it's a 2008. I think the previous owner may have over-torqued the bolts.

We went out and blow kicked up (gusting near 30knts).. back on the beach i noticed one of the bolts had wiggled it's way up by 1/2 a cm. Got the torque wrench out and noticed it was spinning and not getting any tighter.. so i assume the threads popped in the heavy air.. glad the boat held up and didn't break up!
blink.gif


 

jetboy

Super Anarchist
1,595
0
I would drill and tap to the next larger size. Any type of helicoil you'll use will introduce a new metal to corrode. Galvanic corrosion is a likely fact of life. Corrosion between the helicoil and the aluminum plate will be very difficult to remedy if it does become a problem. It's really hard to get the helicoil back out. It also does nothing to increase strength or mechanical properties of the system. Basically you have a choice between adding a third type of metal into the mix, or adding a larger bolt. You have to drill out and tap the hole to a larger size anyway. Why not just use a bolt that fits the new threads? Unless you're needing to keep them uniform or wanting to use a smaller bolt for some reason, I'd just use a larger bolt.

good luck

 

teamvmg

Super Anarchist
1,972
104
Ouch how old is your boat? My family owns an Infusion and I definitely don't want that happening to ours!

These things do happen from time to time on lots of different types of beachcat. its not any design/build fault to worry about - its always down to bolt abuse by operators, over tightening, under tightening, cross threading or not greasing the bolts.

 

Latest posts




Top