Chesapeake Double with Mirage Drives

[BrianP]

Pretty cool boat

http://www.clcboats.com/forum/clcforum/thread/28017.html

This is the standard boat http://www.clcboats.com/shop/boats/kayak-kits/chesapeake-double-tandem-kayak-kit.html

[Tasman]

Very clever modification to the peddle / crank setup on the standard Mirage drive. Well spotted Brian, this gives one much food for thought in using these wonderful drives in other boats.

Cheers - John

[BrianP]

Hi John, do you by any chance have any suggestions for a very light single? 4mm ply and say 10' to 12' long to make it easy to carry down cliff steps.

A local chap paddled past me when I was swimming off the beach the other day in this very tidy SOT, something much lighter in ply with Mirage would be perfect.

http://www.cornwall-canoes.co.uk/wilderness-systems-tarpon-100.htm

Brian

[Tasman]

G'day Brian, I seem to recall that John Harris of CLC had a design for a plywood sit-on-top some years ago. It would not be very difficult to convert something like that to work with the Mirage.

The other approach may be to think about a modified version of the Duo by Richard Woods. Working to lower the midship section tank/thwart by flattening it out, lengthening it. This new "sub floor" would allow the fitting of the Mirage and add further air tight space much like a sit-on-top. With careful construction you could keep the weight down to allow the craft to be carried.

Cheers - John

[Timmo]

You can put a mirage drive into virtually any boat. It's easy to fit a box (like a daggerboard case only wider) to hold the Mirage Drive. Think my Zelva at 17ft long and 4ft 6in wide is probably as big a boat as the drive can reasonably cope with but anything under that will be fine.

Look for designs that have a broad keel plank. At least 6 inches wide at the point where the Mirage Drive will be fitted makes it easy. 

Think about seating carefully. Using a Mirage Drive for any distance from a normal seat can be very painful. A seat with good back support and a reclined position is perfect, but not good for paddling. If you plan on being able to do both pedalling and paddling you may be looking at an uncomfortable compromise.

Tim.

On 25 Jun 2014, at 00:53, Tasman [via UK HBBR Forum] <[hidden email]> wrote:

G'day Brian, I seem to recall that John Harris of CLC had a design for a plywood sit-on-top some years ago. It would not be very difficult to convert something like that to work with the Mirage.

The other approach may be to think about a modified version of the Duo by Richard Woods. Working to lower the midship section tank/thwart by flattening it out, lengthening it. This new "sub floor" would allow the fitting of the Mirage and add further air tight space much like a sit-on-top. With careful construction you could keep the weight down to allow the craft to be carried.

Cheers - John

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[BrianP]

Thanks John and Tim.

I thought your suggestion John to Richard Woods that the Duo could have an extra centre section added which had the case for a Mirage Drive was a really good one, and that it would then be the Swiss Army Knife of boats was spot on. Shame Richard was not on the same wavelength.

For other forum members, the Duo is a new design by Richard Woods which is very lightweight, only 10' long, can be a two piece hull for loading in a pickup truck and is built from just two sheets of 4mm ply. It rows, motors, sails and can also convert to a trimaran!

Link here to the WBF http://forum.woodenboat.com/showthread.php?174949-Richard-Woods-10-Row-Sail-Dinghy-Duo

I think the CLC sit on top was 16' which is too long for carrying down steep cliff steps with turns half way down. A ply version of the 10' sit on top would be perfect.
http://www.guillemot-kayaks.com/guillemot/node/2402/detail
Although my favourite design of all time is the Bootlegger by Guillemot Kayaks and Nick does a smaller solo version at 14' which is just lovely.

Brian

[BrianP]

Jem Water Craft actually describe their plywood Sabolo SOT as inspired by the Wilderness Systems Tarpon.

Here is their 12' Sabolo which uses 4 sheets of 4mm. http://www.jemwatercraft.com/proddetail.php?prod=Sabalo12#BOM does not have the flat centre keel plank but is very low deadrise.

Do you position the Mirage Drive by sitting the crew in the same place as for paddling, then place the drive a certain distance away depending on leg length.

Brian

[Timmo]

Nice looking design.

Only reason I say to look for a flat keel plank is because it's difficult maintaining the integrity of the keel if you cut it completely, the slot for a Mirage Drive is wider than that for a dagger board so it requires a lot more work to carry the strength of the keel past the slot.

In a stitch and glue design there's not the same issue. The monocoque nature of the structure means the box you build to hold the drive will ensure the structure remains rigid. Shaping the box to fit the hull is fractionally more complex perhaps.

The centre of balance doesn't change with the Mirage Drive so I've kept the seating position the same as for paddling. There's some adjustment for different leg legth on a Mirage Drive but using the more extreme positions does compromise the efficiency of the pedalling action. For that reason I've normally built in some scope for adjusting the seat position as well.

Seat design is critical if you plan to spend more than an hour at a time pedalling.

Tim.

On 26 Jun 2014, at 16:24, BrianP [via UK HBBR Forum] <[hidden email]> wrote:

Jem Water Craft actually describe their plywood Sabolo SOT as inspired by the Wilderness Systems Tarpon.

Here is their 12' Sabolo which uses 4 sheets of 4mm. http://www.jemwatercraft.com/proddetail.php?prod=Sabalo12#BOM does not have the flat centre keel plank but is very low deadrise.

Do you position the Mirage Drive by sitting the crew in the same place as for paddling, then place the drive a certain distance away depending on leg length.

Brian

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[Chris Waite]

TimmO wrote -

"....look for a flat keel plank is because it's difficult maintaining the integrity of the keel".  Seems a good moment to point out that the Premise 15 (Rowing Skiff) design 'Curvy Mabel' has just that -

 

He goes on to point out that stitch and glue, monocoque construction largely bypasses that problem, but being flat(..tish) at the right location for the Mirage drive makes it an easier fit.

Further he states -  

"Seat design is critical if you plan to spend more than an hour at a time pedalling."

I can second that too, having spent a week ped-yuloh-ing 'Polly Wee' (this picture actually taken previously by Graham on the Arun) -



Yes, ped-yuloh-ing down the upper Thames among a small, self-selected band of HBB-brothers.  The knees found it er, 'interesting', but much more enthralling was the stinging spinal spasm, only partly relieved by doubling up the back cushion to increase the lumbar support.

This was the fourth time I have done this trip and previously always facing aft, under oar.  It was worth the discomfort though, to see the river and surrounding topography unfolding in front of us, as we progressed.  I'll not be turning (my) back any time soon.

If a picture is worth a thousand words

What value a decent seat?

CW  

[BrianP]

Hugh Horton designed a rather splendid adjustable seat for his lovely Bufflehead design. Hugh describes it here http://www.bootsbaugarage.ch/hugh/h_essay9_en.htm 

and here is Axel's version.

http://www.bootsbaugarage.ch/buff_technik_en.htm#sitz

Might stimulate the grey matter.

Brian

[Timmo]

Some nice ideas there. Particularly the range of adjustments he's incorporated.

Important thing is to recognise the radically different position required for pedalling as opposed to paddling or indeed sailing.

My seat doesn't adjust, it's only for me and only for pedalling. It is very specifically shaped to fit my back and provide lumbar support and it also goes high to support my back right up to neck level (well there's a head rest too for very casual moments.)  I recently moved it aft in the boat by about three inches. Made a huge difference to pedalling comfort. 

On a recent trip I was pedalling (at a relaxed pace) for up to 15 hours a day which gave me time to experiment. I found it better on the back and knees if you are both appropriately reclined, positioned in such a way that your legs are close to full stretch at the end of each pedal stroke and the Mirage Drive cranks are set as near vertical as possible. This last also put least strain on the drive mounting system.

Next thing I want to do is work out how to fit decent toe clips or spd pedals to the Mirage Drive so I can use both the pull and the push stroke to share the load round a few more muscles. There's a guy in Australia that uses Shimano clip on cycling sandals and spd pedals. Only problem is I find the clips on cycling shoes (the mountain biking and touring sort with a good walking sole) can occasionally scrape the ground and I'd be nervous about the damage they could do to a wooden boat.

For those contemplating a Mirage Drive remember they do pick up weed on the fins (maybe more so on the turbo fins) and th instant you do you lose over 50% efficiency. Can be a real pain constantly clearing it if there's a lot of weed, cut grass, plastic litter or anything similar around. Suspect Chris's brilliant pedalyuloh doesn't suffer from this disadvantage.

Tim.

On 27 Jun 2014, at 17:11, BrianP [via UK HBBR Forum] <[hidden email]> wrote:

Hugh Horton designed a rather splendid adjustable seat for his lovely Bufflehead design. Axel describes it here http://www.bootsbaugarage.ch/hugh/h_essay9_en.htm

[Tasman]

Timmo wrote

Some nice ideas there. Particularly the range of adjustments he's incorporated.

Important thing is to recognise the radically different position required for pedalling as opposed to paddling or indeed sailing.
>

Tim makes a very important point about correct seating. I peddle a Hobie i12 inflatable with a Mirage drive and occasionally ride a recumbent trike. In both, the recumbent posture and its critical adjustment is very important for anything but a short trip.

Brian, have you considered approaching John Harris of CLC to see if he would be interested in designing such a craft ? BTW the Duo has a flat underwater midship section much like the one on the Premise 15' craft by Chris W, the perfect spot for a mirage size hole to appear in !

Cheers - John

[BrianP]

I have actually already asked John Harris about CLC doing a Mirage Drive design but John declined. I think it is to do with possible problems with Hobie in gaining commercial agreement whereas it's fine for home builders to create an installation by themselves. He did mention there are a lot of Mirage Drive installations on his forum.

Michael Storer is creating a nice design at the moment with a flat keel plank, first pics on Facebook. Would possibly be good and quick. https://www.facebook.com/photo.php?fbid=10152956220099992&set=gm.783445355022393&type=1&theater

Brian