Rotary vs linear drive for autopilot

The IP35 I purchased 3 years ago came with an old autohelm wheelpilot that is way beyond its useful. the new Raymarine wheelpilot is only rated for 16k displacement, and everything I have read indicates that is overly optimistic. I will replace it with a below deck unit.

My 35 still has the between the legs rack and pinion steering. It looks like a rotary unit could be installed in the housing under the helm seat and the steering sprocket attached directly to the rudder post. The 1/2" key-way on the top of the post looks long enough to accept the sprocket key. The chain would be very short, but the rotary drive would be very accessable.

Has anyone installed a rotary drive on the rack and pinion steering like the IP35? Any thoughts would be appreciated.

I'm in the process of replacing wheel unit with a a rotary type 1, there is a bracket that goes beneath the rack and pinion and a sprocket to the aft end of the wheel shaft between gears and transom. I have the parts, used , and am working on installation, looks like it should work fine. Check photos I've got it up and running , most excellent. QUIET and powerful.

I have an IP 35 #78?
My autopilot is identical to yours as shown,
except the rudder sensor is mounted just under the teak seat
It's a Type 1 rotary drive , and 7000 autohelm control head.
All replacement parts ie. The motor,replacement control head and computer are all available from Raymarine

It shook a little at first, which I attributed to prop wash on the rudder, and/or a lose lower shoe on the rudder....
It took me a while to get used to it, and adjust the rudder gain properly
Now the more I use it, the better I like it.
Ed

Could you share some info on the suppliers of the sprocket and bracket? Also was it difficult to fit the sprocket on to the shaft. Thanks

Sorry. No. I cant help you there...
The. 7000 series autopilot! Chain drive sprockets and chain drive
Were installed on the boat long before I purchased the boat....

Ed

Looks like a real clean job. Could you let me know the sprocket and chain details including supplier along with who fabricated the bracket. Also was it difficult to fit the steering sprocket to the wheel shaft. I'd appreciate a chance to talk if that's ok. regards, Chuck Hodges

Sorry. I was trying to contact the person who posted the photos showing the sprocket, chain and bracket. I'm new to the system and will try again. Thanks

Chuck
Its. OK, I think the rotary drive sprockets and chain , and the welded Aluminium bracket
As shown in the photos
Are identical to the installation in my IP 35
That makes me think that the install must have occured at the IP factory in Florida.
So perhaps you should contact them.. I bett hey will be able to sell you the entire assembly,
Or give u the name of the local supplier from whom they originally obtained the autohelm
Regards

Ed

Chuck,
I took a look at those photos 'Hayden" posted of his install
And I now think his install would be easier to accomplish for "do it yourselfers" like ourselves.
Compare installing a plywood and epoxy shelf to mount the linear drive on
Versus fabricating that Aluminium bracket and obtaining the sprockets as shown in the photos.
Unless you can buy all the parts for the rotary drive, including aluminium bracket, chain and sprockets
Then the linear drive, rudder arm,and plywood /epoxy shelf would be easier overall....
Just my two cents worth
Gee, I find my self agreeing with Hayden- spooky. LOL
Regards
Ed

Chuck, those are my photos The bracket was a trade with the owner of a 32, I believe an IP supplied piece . The sprockets were obtained through merritt gear and sprocket. The chain was a 40 pitch obtained through a local supplier. The drive type 1 .. The sprocket on the steering shaft has a key and set screw. Had to loosen everything and slide the pinion shaft forward a few inches to install the cog . Good reason to clean and lube the steering rack and pinion and all bushings.
This system is really quiet and much stronger than needed for a 31. I will try to help you with any other questions
Thor

I have purchased a linear drive autopilot to replace the wheel pilot on my IP35. Hayden's pictures on installation are great and I will closely follow his example. I have a couple of questions on the Edson tiller arm. Am I correct that the rudder post on the IP35 is 2" dia? Was the arms position secured via key way, bolt or set screws? I also only see 10 and 15 inch arms on the Edson site. Hayden mentioned that 6" would have been sufficient. Just wondering if they offer that length. I will be calling Edson to order the arm, but just wanted to be armed with additional information when I make the call.

Thanks
Dan

I,ve gone the Rotary route and could use some help in getting the wheel shaft loose so I can slip on the sprocket. Talked to Edson and they pretty much said to loosen everything. Any input is appreciated. Thanks

Yeah,
PT blaster, and a hammer!

I contacted Martin gear and sprocket try the web for nearest dealer, on the type 1 drive I used a 40bs12 5/8 shaft with a set screw. On the pinion (steering wheel shaft) a 40 tooth sprocket 40 pitch and 1 inch shaft is what I believe I have, measure yours.. I bought a 40 pitch chain from a local supplier it was sold in a length that gave me a spare, ask for an extra master link. Installing the cog on the steering shaft was easy enough.. Remove wheel, remove 4 bolts on pinion bracket , slide the whole works forward, the shaft is already keyed and a key may be there, mine was still there after more than 20 years. Time to clean and grease the rack and pinion. Slide the sprocket on the shaft , put it all back together, and make sure everything is working freely, tighten set screw . If you got the bracket thru IP Two upper bolts go thru the back pinion bracket, the two lower bolts drill thru the deck in the area under the seat. A few washers may be required to bolt it together. This assumes your vessel has the rack and pinion system.Install the drive loosely. Don't tighten the bolts on the drive motor yet, they should be a little long to allow for a few washers to take any slack out of the chain I used wheel alignment shims from NAPA or any auto part store. Open on one side,way easier to install, trust me. Put the chain over the cog and around the drive gear, cut the chain as required, install the master link. Place a towel under the drive to catch the parts you drop, just saying I've seen it happen, small parts are hard to find even with a big magnet.
When finished you will have a real drive. Quiet , powerful and the pilot you always wanted not the puny under powered noisy and clumsy wheel drive.
Fair winds
Thor

Hi Thor,
I found this post reading through old ones about replacing my type 2 Raymarine rotary drive. Can you tell me if you had to remove the water heater to get access to the port side bolts on the rotary unit or did it all pull up through the small gap with the bracket. I'm a bit baffled how to get to this unit.
Any help would be appreciated.

George Ruth
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Hi Thor,
I found this thread while I was looking to see how I'd replace my rotary drive (type2) on my IP 38. Can you tell me how you got access to the port side bolts holding the unit to the aluminum plate? It appears that I'm going to have to take out my water heater to get to it but I'm wondering if you had to.

Best regards and thanks.
George Ruth

I have not installed one but just replaced one on a 38'. I believe my steering set up is the same as yours and honestly, while it's a great place to have it, it's a NIGHTMARE to get to. My brother in law and I spend 2.5 days pulling out the old one and putting the new one in. Access is the issue. I ended up having to take the water heater out to get to that side of the unit. I like the rotary unit as it's a direct chain and sprocket to sprocket hook up to the steering shaft but it's just a tough one to get to. It may be easier to mount it under the seat somewhere OR off in the lazarette.