Jump to content

Modified IMX 38 rudder on Olson 40


Recommended Posts

Steve Brown of Finco Fabrication made the IMX 38 rudder for my Olson 40.

While it was a very nice rudder, with tons of lift and seemingly low drag, it made for a heavy helm. Soon, we are adding an autopilot, so reducing the helm forces is important to avoid high electrical draw by the future autopilot.

As you can see, there was very little balance, so we cut off about 3" from the trailing edge of the rudder.

Also, the rudder bearings were worn out: during big wave sailing, the rudder would move around noticeably. Hence, new rudder bearings were needed. Jefa spherical roller bearings were installed to replace the original nylon disks.

The new Jefe bearings required some fiberglass work and a new rudder tube (not rudder stock).

To remove the deep rudder, we had to cut a few inches off, and then glue that bit back on after re-installing the rudder.

 

2135785000_Rudder01.jpeg

176549118_Rudder02.jpeg

Link to post
Share on other sites

At Dennis Choate's shop, the rudder was reworked. A line was drawn where the new after part of the rudder would fair into the existing forward part of the rudder, then 3" of the trailing edge was cut off.

881097082_Rudder03.jpeg

48694302_Rudder04.jpeg

Link to post
Share on other sites

A line in the interior foam indicated the centerline, and a solid piece of g10 sheet was inserted into the foam

372213593_Rudder05.jpeg

287994946_Rudder06.jpeg

Link to post
Share on other sites

The Jefa bearings are bigger, so that required a new rudder tube. The new tube is stronger with gussets to spread the load -- a lesson from the bigger sleds

261051582_Rudder08a.jpeg

1700385987_Rudder08b.jpeg

Link to post
Share on other sites
23 hours ago, carcrash said:

we are adding an autopilot, so reducing the helm forces is important to avoid high electrical draw by the future autopilot.

Rudder looks great.  Are you going with a tiller pilot or did you modify the tube so you can add an arm and a below deck AP drive? 

 

Link to post
Share on other sites

I have an arm below, and all the structure for an under deck autopilot drive. The boat originally had a very custom and complex autopilot using an under deck Octopus integrated hydraulic unit. But am considering a Pelagic tiller pilot.

I would rather have the drive down below, but that requires two things: 1) it needs to be quiet, as noise really travels in my open plan boat, and 2) it needs to be VERY low drag when not being used, as I really like to helm the boat.

A tiller pilot puts the noise outside, and can be disconnected from the tiller entirely so no drag when not being used.

An underdeck unit provides one HUGE advantage: the tiller can be raised, tied to the backstay, and so 100% out of the way when under autopilot. Just like when anchored, in a slip, on a mooring, being able to get the tiller out of the cockpit when not being actively used is a big win.

I may just write the check, and run the experiment, as the opinions and reports I have heard are not consistent on the noise nor on the drag: some say noisy, some say silent, some say annoyingly draggy, some say no drag. So I can't find consistency in reports online. No surprise of course!

Link to post
Share on other sites
2 hours ago, carcrash said:

I have an arm below, and all the structure for an under deck autopilot drive. The boat originally had a very custom and complex autopilot using an under deck Octopus integrated hydraulic unit. But am considering a Pelagic tiller pilot.

I would rather have the drive down below, but that requires two things: 1) it needs to be quiet, as noise really travels in my open plan boat, and 2) it needs to be VERY low drag when not being used, as I really like to helm the boat.

A tiller pilot puts the noise outside, and can be disconnected from the tiller entirely so no drag when not being used.

An underdeck unit provides one HUGE advantage: the tiller can be raised, tied to the backstay, and so 100% out of the way when under autopilot. Just like when anchored, in a slip, on a mooring, being able to get the tiller out of the cockpit when not being actively used is a big win.

I may just write the check, and run the experiment, as the opinions and reports I have heard are not consistent on the noise nor on the drag: some say noisy, some say silent, some say annoyingly draggy, some say no drag. So I can't find consistency in reports online. No surprise of course!

With the new rudder profile, and an Olson 40 being reasonably light, you could theoretically getaway with a removable tiller pilot up top. I also have an extremely high aspect rudder and my borderline undersized Simrad keeps up just fine. You can see the attachment for the tiller pilot on the underside of the tiller. It’s got almost no leverage, but does just fine. 

DA7BF606-64C3-4046-828C-6ED794BEC317.jpeg

Link to post
Share on other sites

Seems like a short tiller to tiller pilot with a longer tilting tiller could provide that utility. I put the stud on the bottom of my tiller with a bungee holding up the tiller pilot.  Easy quick disconnect by pushing it down and it hangs on the bungee 

  • Like 1
Link to post
Share on other sites
On 10/14/2021 at 4:06 PM, carcrash said:

I have an arm below, and all the structure for an under deck autopilot drive. The boat originally had a very custom and complex autopilot using an under deck Octopus integrated hydraulic unit. But am considering a Pelagic tiller pilot.

I would rather have the drive down below, but that requires two things: 1) it needs to be quiet, as noise really travels in my open plan boat, and 2) it needs to be VERY low drag when not being used, as I really like to helm the boat.

A tiller pilot puts the noise outside, and can be disconnected from the tiller entirely so no drag when not being used.

An underdeck unit provides one HUGE advantage: the tiller can be raised, tied to the backstay, and so 100% out of the way when under autopilot. Just like when anchored, in a slip, on a mooring, being able to get the tiller out of the cockpit when not being actively used is a big win.

I may just write the check, and run the experiment, as the opinions and reports I have heard are not consistent on the noise nor on the drag: some say noisy, some say silent, some say annoyingly draggy, some say no drag. So I can't find consistency in reports online. No surprise of course!

How are you disconnecting the pilot so I doesn’t drag?

Link to post
Share on other sites

Monkey and Dumas, thanks for that feedback.

Perhaps I could put the tiller pilot, that is easy to disconnect, under deck on the under deck tiller arm I have for an under deck drive. Maybe. I'll have to try some things... The backlog for new autopilots is three to six months.

 

Link to post
Share on other sites

I have an under deck Raymarine linear mechanical drive on my boat, about the same displacment and similar rudder. It works well and the motor is silent from the cockpit. It does clunk when stearing as there is some necessary play in the mount. 

The drive has a clutch so resistance is minimal. My boat has a wheel, but it is very light and less than a full revolution lock to lock and I still have good helm feel despite the drive. As always experiences vary, but it is worth a look.

My last boat had a tiller pilot. The convience of the under deck unit being ready to go all the time by hitting a botton on the control panel was a game changer.

Link to post
Share on other sites
On 10/22/2021 at 9:04 AM, steele said:

I have an under deck Raymarine linear mechanical drive on my boat, about the same displacment and similar rudder. It works well and the motor is silent from the cockpit. It does clunk when stearing as there is some necessary play in the mount. 

The drive has a clutch so resistance is minimal. My boat has a wheel, but it is very light and less than a full revolution lock to lock and I still have good helm feel despite the drive. As always experiences vary, but it is worth a look.

My last boat had a tiller pilot. The convience of the under deck unit being ready to go all the time by hitting a botton on the control panel was a game changer.

Thanks for that feedback, Steele. 

The under deck actuators seem to always have clutches that consume about 12W (1A) continuously. That seems a large percentage of the total autopilot draw. Other than the clutch, in most conditions my boat requires no movement of the tiller once weather helm is dialed in. I can use shock cord for extended periods of time. So in my case, where my boat has very good directional stability, I might see a majority of autopilot energy consumption being that clutch. 12W x 24 is a 288 watt hours per day. Our refrigeration consumes abut 600 watt hours per day. Not a deal breaker, but an eye opener.

For convenience (instant on/off), and for the ability to get the tiller out of the cockpit, I am very strongly attracted to the under deck ram.

Really, I might just buy both, and see. It's a small number of boat bucks, as installation of the under deck ram is already done, and installation of a tiller pilot is always simple. Redundancy is not evil.

Link to post
Share on other sites

I was not aware of the power draw from the clutch alone. The boat was purchased with the autopilot installed so I did no research. We do not do extensive offshore or overnight passages so it is not really an issue, but still good to know. It is important to keep track of parasitic loads, like our popane solenoid which also draws 1A when energized. Our fridge draws about the same as yours. The addition of a 110W flexible solar panel this summer reduced battery capacity anxiety significantly.

Link to post
Share on other sites

so, my 30 footer has the usual single rudder post, but two tillers. The usual one above deck, but another below deck at 90 degrees. This second tiller is steel and keyed onto the rudder post - its there because the boat originally had a wheel. but no quadrant. The wheel had a solid linkage, with a couple of universal joints, that operated the below-decks tiller.

My question: does anybody see a problem with mounting a tiller-pilot to my 90 degree offset tiller arm below deck? This part of the boat is not easily accessible, so I would have to add some new access hatches so that I could readily detach the control arm. But, otherwise, this seems like it could have some advantages over a deck mounted tiller pilot as the tiller can be lifted out of the way while under autopilot - and it will also be out of the weather.

Link to post
Share on other sites
On 10/24/2021 at 12:55 PM, carcrash said:

Thanks for that feedback, Steele. 

The under deck actuators seem to always have clutches that consume about 12W (1A) continuously. That seems a large percentage of the total autopilot draw. Other than the clutch, in most conditions my boat requires no movement of the tiller once weather helm is dialed in. I can use shock cord for extended periods of time. So in my case, where my boat has very good directional stability, I might see a majority of autopilot energy consumption being that clutch. 12W x 24 is a 288 watt hours per day. Our refrigeration consumes abut 600 watt hours per day. Not a deal breaker, but an eye opener.

For convenience (instant on/off), and for the ability to get the tiller out of the cockpit, I am very strongly attracted to the under deck ram.

Really, I might just buy both, and see. It's a small number of boat bucks, as installation of the under deck ram is already done, and installation of a tiller pilot is always simple. Redundancy is not evil.

I like the way you think. An under deck autopilot with a back up tiller pilot is a surprisingly simple, yet effective idea. 

Link to post
Share on other sites
On 10/30/2021 at 6:46 AM, ROADKILL666 said:

Nice boat porn thanks. Got more pics of your baby?

Yes. In different topics.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...