Rudder shear bolt?

[bogieboy]

So as some of you know i am building up an old Dumas DV-60cf 45" hull with a gas engine....so a fairly heavy boat... i also custom built (with the help of my machinist buddy/coworker) a rudder from scratch... its all together but i cannot figure out what way to go for the shear bolt of said rudder... i currently have some 10-24 nylon bolts, and some m4 grade 8.8 bolts floating around.... i have not drilled the bolt hole in the rudder pivot yet.....which would y'all recommend? Or should i get something brass instead?

[30nitro]

I run both nylon and brass rudder shear bolts.....on that size hull.. i might run brass...but it's sorta up to you..depending on the water you're runnin in.... I'm usually in clean water....

[bogieboy]

I wouldnt consider my typical water trash laden, but also not exactly clean...LOL erie canal is less than a 1/4 mile from the house...or a few min drive to a wider portion of it...

[785boats]

I find that a pivot bolt, & a slot with a steel bolt works well. No need to replace broken bolts then.
The bolt in the slot is tensioned to hold the rudder during normal running but allows the rudder to pivot when it hits something.
This also allows for toe in & toe out adjustment for tuning the boat.

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[NativePaul]

Most of the monos I see use a single bolt so it is free to pivot, and a spring to keep it down. That way it will kick back if it hits something, then goes straight back into place so you can finish the race.

[ray schrauwen]

Most of the monos I see use a single bolt so it is free to pivot, and a spring to keep it down. That way it will kick back if it hits something, then goes straight back into place so you can finish the race.

They used to sell those, made by Vantex. I have not seen them for a year or two.

[ray schrauwen]

They still sell them at Hobby ease. Don't know if I trust them.

[785boats]

Ray.
I buy gear from Hobbyease. My race winning cat is from there. They're OK.
I've always meant to try one of those rudders, but just never got around to it.

[NativePaul]

Hmm, the shock absorber seems counterproductive to me, if it hits something you want it to move out of the way ASAP with as little resistance as possible. Not the lightest solution either, most folks just drill a hole in the rudder blade then run a tension spring from there to the transom or a bolt in the rudder support.
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[bogieboy]

Hmmm interesting ideas.... the overall design of the rudder kinda prohibits the options other than a thru bolt though... i wasnt around for the actual cutting of the blade slot, so it is larger (and deeper) than it really needed to be... the rudder blade is shimmed so it has a contact fit at the pivot but the slot is overly deep as well, so the spring option would pull the rudder back over center... and i dont think the pinch bolt ideal would hold either unfortunately... :-/

[NativePaul]

You could always build the slot back up with epoxy putty to shim the rudder so it gets pulled to the right angle, or drill and tap it near the slot for a grub screw that you can easily adjust the angle with.

[RCBoaterGuy]

Plastic probably not strong enough for that app.

Here's how PB did it with the IM31's... https://www.horizonhobby.com/rudder-...3Aim31-prb4257 - if memory serve's me right, the larger one is M4, while the smaller one is M2.5

For your app, I would use either a M2 or M2.5 for the shear screw / bolt. I buy in bulk from this place.. https://www.albanycountyfasteners.co...screws/693.htm - most of it goes to my trucks.

If I need an odd size (used all M2 stuff for HK Swamp Dawg build currently in progress), then I'll wait & add it to the next order.

Hope that helps, good luck with the build!