<> what's the latest thinking on retractable skegs? | Kayak Forum

what's the latest thinking on retractable skegs?

Submitted by howard on Mon, 09/03/2018 - 22:39

hi all, 

its been  a while and i am working on a new project....a 90% frej (15 ft length and 19 inches beam) that i am trying to build up very light for my wife.

the basic approach is 3/16 red cedar with 4 oz s glass inside and out, internal seam kevlar taped,  keyhole cockpit and a target weight fully rigged of 22 lbs.

given the hull form, it looks pretty important to have a skeg and wanted to see if anybody had suggestions for good plans that are easy to build or a well constructed skeg that can be bought/installed.

i just finished glassing  and fill-coating the outside of the deck and hull....so i am not that far away from having to decide on how to approach the skeg.  keeping it light but reliable and to work with the aesthetics of the boat is important to me as well.  any suggestions/thoughts appreciated.

h

frej 90 deck fill coat

 

JohnAbercrombie

Tue, 09/04/2018 - 01:56

Howard-

Do you want a cable ('push') skeg or a rope control skeg?

Bjorn Thomasson has some skeg info on the website; you've probably seen that.

Lots of folks have built their own 'from scratch' - Etienne Muller has info and good pictures of his.

It's a fair bit of work to build a good skeg from scratch, I found. Which can be part of the fun.....

Another approach which I've seen in some commercial kayaks is to use something like the KajakSport skeg and completely encase it in  glass on the inside. Getting a good seal at the cable exit from the box is important.

If you  are trying for a 22# kayak, you'll probably want the lightest and simplest option you can find. 

I put a 'skeel' (skeg just abaft the cockpit) in my Frej builds (16' and 18') and find it works better in the shorter boat. An aft skeg would have a bit more authority to keep the 18' Frej tracking easily in side and following winds.

YMMV, etc etc...

etienne, john,

thanks for the notes.  in answer to one of the above questions i want to use wire like a push rod to push/pull the skeg up/down.  i was thinking 18 guage (approximately 1 mm) wire.  do you have a wire manufacturer or specification you recommend that is also appropriate for marine use?

do you also have any more details on how you executed the control box?

below is a plan that i am modifying to not work with lines but with wire  (not a very clean drawing...but the pencil marks are where i am doing the redesign work)   i don't have a lot of deck height so the idea is to move the axis down low allowing the push/pull wire to come in at the top of the box with a very low angle to fit under the low deck.  the approach allows the top of the skeg (most forward part when retracted) to be almost vertical) minimizing the size of the box/skeg relative to the in-the-water portion...which should save a couple grams:).

anyway...have been doodling all night....will think upon it some more.

h

drawing up a skeg with modifications

 

Etienne Muller

Wed, 09/05/2018 - 03:56

My control box is very simple. The hinge on the skeg allows the cable to move with very little resistance, and the knob only needs to move an inch and a half to fully deploy the skeg, so there is no chance of the cable kinking.

The photo tells the story.

Control box

Control 2

3

JohnAbercrombie

Wed, 09/05/2018 - 13:02

Howard said:

..... i want to use wire like a push rod to push/pull the skeg up/down.  i was thinking 18 guage (approximately 1 mm) wire.

Commercial skegs that I've seen use at least 1/8" (~3mm) 1 x 19 stainless wire.

I think some amateur builders have experimented with using carbon fiber push rod material, as used in model planes and boats.

JohnAbercrombie

Wed, 09/05/2018 - 13:12

Etienne said:

The hinge on the skeg allows the cable to move with very little resistance, and the knob only needs to move an inch and a half to fully deploy the skeg, so there is no chance of the cable kinking.

There are a couple of fairly common causes of skeg wire kinking.

Any unsupported skeg wire (i.e. not in a tube or channel) can kink if enough force is applied, and the longer the unsupported length, the easier to kink.

Scenario 1: Launch from a sandy (or worse, fine pebble) beach with a pebble or sand jammed in the skeg box - usually this happened earlier when landing. Try to deploy skeg; push hard on the knob.

Scenario 2: Forget to raise skeg when landing, or hit an underwater rock at speed. If the skeg control is stiff, the cable can kink.

You need to have some friction in the cable if you want to keep the skeg in its set position.

 

Don't forget to put a 'string' on your skeg so your paddling partner can pull the skeg out of the box for you, when afloat. If you paddle solo, check Freya Hoffmeister's blog for a nifty system for skeg 'pull-down' when jammed.

 

I use Nick's plans for the skeg, with one exception: I make the control knob and blade out of lexan. This gets me out of a few fill/drill/re-drill steps. A plug cutter drill bit makes the spacers around the pivot point nicely.

A lexan skeg

I've recently put one of Nick's skeg in a Petrel and been very happy with it, and would probably go this way in next build as well. 

That said, I've also retrofitted a Superior Kayaks kit into another build and been very happy with it.