Tillerarm radius for linear drive autopilot installation

[Stuermer]

Hi All;
I am about to install a new Raymarine Type 1 linear drive autopilot system on my Beneteau 331.
The drive unit is spec’d for up to 22,000 lbs so way overkill for my boat…until I consider the limited space for the install.
In fact, I don’t have enough room aft of the rudderstock for the required 10” tiller arm radius and I am hoping to avoid installing forward of the rudderstock and intruding into my aft cabin.
Can anyone please tell me the formula for calculating the minimum tiller arm radius I can use to still support my ~11,173 lbs (empty) boat?
I thought I saw it here some time ago but am not able to find it now (been searching for two days now).
cheers and hang in there - only 4 months till launch here in Canada.

 

[dlochner]

Have you contacted Raymarine?

 

[Stuermer]

No. Just thought someone might have the formula since I’ve already seen it somewhere here.

 

[dlochner]

No. Just thought someone might have the formula since I’ve already seen it somewhere here.

Not to slight any of my fellow posters, but for something this important and fairly esoteric I'd go with RM's advice. It is possible that not following RM's advice will void the warranty.

 

[Stuermer]

Excellent point. I’ll contact them.
Still hoping for feedback from objective fellow sailors, though.

 

[JohnShannon]

half the weight, half the distance, Then of course you are using it at its limit. On the other hand I would say the entire exercise is more like what you might call a suggestion. I feel confident in stating that if you hooked that up to the wheel of the Nimitz (200,000,000lbs)
it would work fine. So there is more at play here.

 

[Len Ingalls]

Is it the electric linear drive M81130 series? Ray Mechanical Linear Drive (M81130, M81131, M81132, M81133, M81134) Installation Instructions 81175

Attaching ram to quadrant - Page 2 - Cruisers & Sailing Forums

Don't weld on your quadrant. The approved way to connect an a/p ram to a mechanical steered boat is to install an auxiliary, below-decks tiller arm, such as supplied by Edson , for just such purpose.

www.cruisersforum.com

 

[Stuermer]

Thanks, Len, I read that, too.
Unfortunarely there is no room or exposed rudderstock. However, there are threaded holes on the quadrant and I have seen pictures on this forum where owners of similar boats have attached the drive.
The manufacturer of my steering mechanism is Whitlock but I have not been able to find a contact to verify material or other specs for my quadrant.
I think it’s cast aluminum or other metal.
Does anyone have any info on the steering system/quadrant on a 2002 Beneteau 331?

 

[Stuermer]

@ dlochner. RM replied with ‘no less than 8” ‘ for the Tillerarm. That’s no problem for me. Thanks!

 

[Stuermer]

Yes

Is it the electric linear drive M81130 series? Ray Mechanical Linear Drive (M81130, M81131, M81132, M81133, M81134) Installation Instructions 81175

Attaching ram to quadrant - Page 2 - Cruisers & Sailing Forums

Don't weld on your quadrant. The approved way to connect an a/p ram to a mechanical steered boat is to install an auxiliary, below-decks tiller arm, such as supplied by Edson , for just such purpose.

www.cruisersforum.com

Yes, it is the type1.

 

[dlochner]

The manufacturer of my steering mechanism is Whitlock but I have not been able to find a contact to verify material or other specs for my quadrant.

I believe Whitlock was bought by Lewmar. Check out the Lewmar site.

 

[Stuermer]

I believe Whitlock was bought by Lewmar. Check out the Lewmar site.

Yes, thank you, there is a link to the new website and I have even sent an email to their ‘contact us’ address to no avail.
Very disappointing.

 

[thinwater]

Pictures really help. There may be another clever idea.

 

[Apex]

I think it is more about stroke than power. I purchased ML+40-8 (B&G T0 linear drive). At 175mm from center of the rudder shaft, the drive pushes through an ARC. Shorter arm creates a larger arc it acts through.
I will be trying to find anyway possible to avoid the quadrant for installation, creating full redundency.

 

[Len Ingalls]

The Raymarine Type 1 Linear Drive (M81130) has a 12" stroke. The mid stroke point (rudder centered) is 6" from tiller arm & 6" to fully retracted.
If you use a tiller arm which is 6'' from center of rudderstock to the heim/rose joint attachment of the ram &
fix the back end of the ram to the vessel so that a rectangle is formed(4 corners at 90deg),then
full 6" stroke from rudder center to ram fully extended or retracted will give you +/- 45deg of rudder.
If you shorten the tiller arm,you will get more than +/- 45. If you lengthen the tiller arm you will get less than +/- 45 deg.
IMHO-the ideal in this case is +/-45 deg.
Note: You should fix mechanical rudder stops before +/- 45deg,to prevent full extension of ram.
See att: