Tuning for Performance

The emphasis here is on maximizing cruising range while minimizing fatigue. Small gains in speed (.1 to .25 MPH) may be obtained as well. Keeping in mind that a 1/2 kt. increase in speed requires almost twice the power, the higher priority here is in extending your speed over time by improving efficiency and reducing friction.

In optimizing your kayak, we can look at four components -- the Drive, Drive-user interface, rudder and hull.

Drive: The most important improvement you can make to your Drive is removing as much friction as possible. The acid test I use is to hold the Drive upright by the right crank arm, pull the left crank arm back and see what happens.

If it doesn't move, the Drive gets an "F". If the left arm swings without assistance all the way back to center or more, that's an "A-";

If it goes past center and returns to center, the Drive gets an "A+" (assuming Turbofins -- smaller fins won't swing quite as much). Every pound of resistance on those pedals represents about 1 1/2 +/- tons of friction instead of thrust per hour and is a major component of fatigue! To review adjustment and lubrication procedures, see: http://www.hobiecat.com/community/viewtopic.php?t=6418

Next lets look at equipping the Drive. Since '08, all Drives come with a "drive well seal" or swisherator.

This prevents some of your hard earned thrust from surging into the boat during the fin cycle. You can easily retrofit these on all the older drives. and this will actually give you a small gain in speed.

A couple of quick notes on the Drive: Some consider the foot straps annoying -- if you learn to use them, they can keep your feet in position and potentially make the pedaling effort more efficient.

Most don't use the pitot tube speedometer, even if they have one. I find it indispensable for assessing actual speed in the water. Used in conjunction with your GPS (logging distance and time) it can detect currents and tides down to .01 MPH. It also can alert you to any seaweed, eel grass or other objects fouling the Drive or rudder. Finally, it is a great pacing aid for distance -- better than a GPS. The calibration units are nothing more than a relative index, but the tube gives very consistent and immediate readings. Mine (shown below) goes everywhere the Drive goes and I rely on it heavily.


Next is fin selection. Both the ST Turbofins and ST fins are more efficient than Standard fins and are an excellent choice. Personally, the Turbofins are an easy first choice, but the STs are quite decent as well. With either, proper adjustment of the clew outhaul is important. Fins should be adjusted "loose", allowing them to twist easily and wind up the mast without restriction ( I know, this is not what the Hobie instructions say). They should tuck in to the clew outhaul slightly and look something like this:

If using the older style Drive, look for at least 1/4" free movement space for sliding up and down the mast. Use Locktite (blue) to secure the adjustment screw if it slips out of position.

Drive-user interface: This area is often overlooked, yet almost as important as the Drive set-up. Ideally, the pedals should be adjusted so that your legs are fully extended at the forward end of the stroke, without hitting the limit of the Drive. Why? The more extended your legs are, the greater the biomechanical advantage. This is also easier on the knee joints and a huge element in muscle fatigue. Feel free to experiment here by moving your pedals an additional notch forward. This shortens your stroke more, increases your cadence and may be more comfortable over time.

IMO, seat comfort is a performance item when it comes to extended range operations where you're pedaling without a break for an hour or more. I like Hobie's new air cushion seat for greatly improved comfort and increased blood circulation to the legs, and have become totally spoiled by it. However, if you're comfortable with the standard seat pad, it may not be that much of an issue.

Rudder: Rudder selection and adjustment should be considered part of any performance tuning. Switching to the large ("sailing") rudder is the best single equipment performance upgrade you can make, regardless of your boat or usage. It may occur to some that a smaller rudder has less surface area and therefore less friction.. This may be theoretically true in calm water with straight tracking, but realistically with the Hobie rudder, this is not the case. The large rudder gives better course control with less tending and eliminates constant correcting, especially in more active water. That's where your performance comes from. Add this to more dynamic handling and there is absolutely no comparison, especially with the Adventure (which barely turns without it).

In order to obtain full rudder authority and deflection, the directional control lines should be taut when the rudder is deployed and centered.. All you need is a Phillips head screwdriver to make the adjustments

First, deflect your tiller or rudder control full left and right, and [using a cardboard template or bevel square (shown)] check the deflection angles at the rudder in both directions.

Any slack in the line should be first removed on the side that has the least deflection. Fine tune the lines accordingly to obtain equal rudder deflection from the tiller. Do not make your adjustments based on pushing the rudder back and forth, as this is not how the rudder is operated!

Shown here is a modified rudder shaped from an old style sailing rudder (still available) trued and remounted forward to eliminate any gap behind the skeg. It us extremely accurate and has excellent authority while minimizing drag.

While something like this is beyond the scope of our discussion, it illustrates what can be done with factory parts.

Hull: The hull is the biggest source of drag. Not much can be done about induced or form drag, but your glide can be improved somewhat by minimizing skin friction. Any raised areas from scratches can be addressed with a razor blade as shown here.


Using clear packing tape, seat scuppers can be streamlined (by covering the first 2/3 of the openings, water will actually be sucked out with forward motion by the venturi effect, even if you're sitting below the waterline as with the Adventure or Revolution). You can also tape cargo scuppers (if not using the cart), mast plug and daggerboard well (Adventure only)


A clean hull moves through the water faster than a dirty one. There are many cleaners -- Hobie sells a cleaner and UV protector that is apparently environmentally friendly. I use the protector on the bottom (rather than the top) of the hull once cleaned. It's very slick -- be careful that your boat doesn't slide off your transport if you use it! I don't know if it speeds the boat up, but I like it.. Wax is OK but does tend to slow the boat down slightly.

If you address these areas, you should be cruising effortlessly within the capabilities of your particular model!

Thanks Roadrunner for all your excellent posts.
I want you to know that your time and effort is much appreciated and highly regarded. I have used several of your suggestions and it makes for enjoyable kayaking.

I purchased the ST turbo fins and will pull up your past article on how to properly install them the first time. The key for me is THE FIRST TIME.

Bruce

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Everything before 60 is just a rehearsal!

Great post roadrunner! I tried your test on my drive with the s/t fins scored an 'F'. Tried making the adjustments and lubricated, still an 'F'. What would you suggest to lessen friction?

I would hazard a guess that the cables are too tight. The 2 mirage drives that came with my 2 '06 Islands were way too tight from the factory. They would get an 'F' as it took an effort to even move the arms.

With cables loosened and lubed they were fine.

Roadrunner once again has created a great post worthy of bookmarking for future reference.

Collect all of Roadrunner's tips into a book and you will have the ultimate in an owner's manual.

Bj, it's hard to say without seeing your Drive, but as Yakaholic says, there are factory tuned Drives that would get an "F" on this scale. Excessive cable tension can cause a lot of friction! This is what I think happened:

The older Drives used a stainless sprocket with nylon bushings. Its Achillies heel was the tendency to skip a tooth if cable tension was too loose. So it was set purposely a bit tight at the factory to allow for a short break-in period without problems.

The newer plastic sprockets were designed to cure the skipping problem (the fat master link plays a part in that), so cable tension became less critical. More recently, Hobie has pioneered the development of glass filled nylon with superior bearing surfaces and improved wear characteristics. Not only do the current drums and sprockets last longer, but there is much less break-in. Unfortunately, many of the Drives were still set to the old standards up until about 18 months ago, so there are a lot of Drives that are tighter than necessary. Most users don't know the difference and attribute any fatigue entirely to the propulsion effort.

There are a couple of other reasons your Drive may have excessive friction. The Drives come with a greased sprocket shaft, drum shaft and idler shaft. Without any subsequent lubrication, this grease can gradually dry out, losing its lubrosity. Water has lubricating qualities, so this is not critical, but certainly not optimal. The lighter lubes will eventually rejuvinate it.

If the Drive is operated frequently in the surf zone, sand can get stuck in the bearing surfaces. If this is the case, you can tell immediately by the gritty feel. The only thing to do is disassemble the Drive and thoroughly clean and re-grease it -- or live with it.

As you get more comfortable adjusting your Drive, you'll acquire a sense of what works best for you. BTW, once you start adjusting the cables I recommend using Locktite (blue) on the cable adjustment nuts to keep them locked in place, especially with the '08 and newer cables with slotted shafts; or any time you experience a change in cable tension that could be caused by the nuts backing out. The Nyloc nuts are very good but these slotted shafts tend to cut into the "nyloc". Even with the older cable shafts, the nylon starts to lose its grip as it is moved up and down the shaft. Locktite cures everything!8)

Thanks for all the useful information. My mirage drive still feels fairly stiff after about 20 hours of use (it scores an 'F' using roadrunner's test). I disconnected the cables and chains, and the resistance seems to be coming from the drum-axle interface. Is this normal, and if not what can be done to free up the drum movement?

Perhaps I opened up a can of worms here. I meant to show what is attainable and how to check for it. How freely each Drive operates depends on its cleaning and maintenance intervals, lubricant, lube points and condition of the Drive components.

Jhart, how much resistance are we talking about? With the chain/cables removed, slide the drums off the axle and make sure they are greased. If they appear a little tight but are rotating smoothly, that's just what you want. They will wear in with time. (If it seems stiff, you can add a dab of light lube to fresh grease to loosen it up just a tad).

Let me repeat, if you don't have Turbofins, you won't get quite as much response on the test, as the Turbos with longer masts are a little heavier and exert more gravitational pull. Drives with smaller fins may not get in to the "A" range. Also, when the Drive is new, it can hang-up on the master cog when the pedals are fully split. This also diminishes in time. The Drives actually seem to improve over time as you work at it.

Maybe we should say that any Drive with any fin combination that returns at least half way to center passes well enough so that friction is no longer a major issue. Better than that is good.

I didn't plan to go into a detailed lube and adjustment discussion here, as they are covered elsewhere. But check your lube points and lubricant. Briefly, I use Breakfree (other low friction lubes like Triflow are doubtlessly just as good) to lubricate everything that rubs or moves -- about 14 points. The Drive is rinsed and lubed every 1 to 3 outings, depending on fresh or salt water and turbidity.

Starting at the bottom and working up, these are the 14 locations:
--front and back of each sprocket where it rotates on the shaft = 4
--each chain on both sides = 4
--inside edge of drum where it meets shaft at spine = 2 (note, I don't recommend the outboard edge of the drums as this may thin your drum grease out too much and dissipate it)
--front and back edge of idler pulley = 2
--pedals where they pivot against crank arm = 2

Spin everything around a couple of times and wipe off any excess oil. It takes about a minute with practice.

Hopefully, everyone with a high friction Drive can at least make some noticeable improvements!

I think the grease Hobie uses on the drum shaft gets a little gummy and actually appears to dry out. Maybe this is caused by silt, salt water or other contaminants.

Clean off all the gunky-grease and use a ligter lube. I like 3-in-one oil, you can get a can that has a very long tube/spout to get to the inside of the drum area. WD-40 then gets used as a quick lube after wash down. (You can get WD-40 in a 1 gallon container w/ a non-airisol spray bottle - a very cheap & enviornmentally friendly way to buy product)

I have seen other users beach their Hobie with the mirage drive still in place. Ya, the flippers are bungied up & safe but the moving parts are all resting on sand/dirt. That forces grit into the mechanism and will create friction and premature wear. I always leash and remove my drive before beaching - that's what the paddle is for.

Although it sometimes gets messy, I'm a bit more of a grease fan. IMO, it plays a vital role in the operation and longevity of the Drive.

The pedal test above is a no load test and is good for assessing no load sources of friction. Pedaling puts a load on the Drive though and we know (for example, by overtightening) that the Drive easily picks up friction under load. That's why I think Hobie uses grease on the three axles. It holds up without washing out, limits penetration by sand and silt and has superior load bearing characteristics. This has been proven over the years on bicycle cranks and wheels and of course automobile wheels. I don't know what Hobie uses, but I use a marine axle grease (commonly used on boat trailers).

The drumshaft probably gets the toughest assignment. The load is off center so the drumshaft wears in an uneven, elliptical pattern, primarily on the outboard side. As a result, it starts wobbling as it wears. It starts out like this:


In time, a gap develops. Light oils are flushed out quickly and debris can enter. This further accelerates wear.


Grease stays in place though to handle the bearing load and minimize wear.


I agree with Yak that, without attention, the factory grease appears to dry out in time. Interim lubing with light oil will keep it moist. Every 300 miles or at least once a year it's probably a good idea to strip, clean and re-grease the Drive.

Roadrunner, of course grease is best and oil/WD-40 for inbetween the times when you grease the spline.

But disassemble for me would be about 1 a month to do it right and it is a real PITA. Plus the nylock nuts then need replacing.

Since we agree regular greasing is good why not add the part that Hobie forgot. A grease fitting. See my new thread on adding one.

Great Post... I did some tinkering with my boat last night, looking forward to seeing the differences.

Awesome post mate, great info for all there.

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Brett Ozanne

www.yakass.net - www.sailpower.com.au - www.westernangler.com.au

www.yakfishwest.com

I agree with keeping the drive lubricated and good ol grease works well. I have a different take on wd 40 being a cyclist. Wd 40 really breaks down the grease quickly making it easy for the water to then just wash it out leaving you with unlubricated parts. Has anyone tried any cycling lubricants? They are designed to resist picking up dirt but yet they dont break down the grease. Just a thought, I dont want to take away from recommendation of the manufacturer.

Now this is a place where I have a bit of experience, marine lubricants have some really gr8 qualities that will lend themselves to our applications Mercury Marine has a product called Special Lube 101 it has a rather thin viscosity but has gr8 cling so for us it'll get around the parts and not wash out.

Also Bombardier(you know the people who make Sea-Doo)make some really gr8 lubes also 1 that I'm particular to is there waterproof synthetic grease I use this stuff everywhere and it really lasts with incredible protection they also make a spray lube that is a anti-corrosive lubricant that has really gr8 staying power 100times better than WD40.

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Fastfish/Geoff
Kayaks Owned>Outback/Mine & Revolution/Wife

Installed the new V2 sprockets and masts to further improve the reliability of the turbo and st fins on my oasis, also added the grease fittings as per Yakaholic's recommendation, greased and readjusted drives as per Roadrunners suggestions....... Drives now rate an A+! What a difference! Took it out today for a good hard ride before the snow starts and it gets to cold out. Very pleased with the results. Thanks guys for the advice and detailed pics that made the job very easy.