Tiller Pilot on Auxiliary Rudder ?

[Boracay]

Boracay has wheel and cable steering and I was planning to fit wind vane self steering with an auxiliary rudder with a tiller pilot for steering while under power.

That was until I found what wind vane self steering costs now and thought about how I'd feel about having a deca boat buck's worth of bling hanging off the stern.

When I looked more closely at the associated auxiliary rudders used they all seem quite small, and I thought that one of the bigger tiller pilots could possibly drive a 3 sq. ft. or so auxiliary rudder hanging right off the end of the boat.

Something like the Simrad TP32 is what I'm thinking of, but they only rate it for boats up to 6.3 tonne and 39' while Boracay is 44' and 14 tonne or thereabouts. Does have 85kg of peak thrust though.

It would certainly make life a lot easier if it will work as it can be integrated with a wind sensor, GPS and a plotter.

So has anyone any thoughts or experience with large tiller pilots?

[4900bruce]

what happens to extra rudder hanging of transom when motoring in reverse

[Boracay]

I'm anticipating that the auxiliary rudder would either be removed or lashed in place when inactive.

Same as the auxiliary rudder on some wind vane self steering gear.

[svHyLyte]

In re: Auxillary Rudders, you might want to look at http://www.selfsteer.com/products/sos/index.php

[Boracay]

Thanks to svHyLyte for the web link. It's exactly what I am thinking of.

Their larger version is probably what I'd aim for, though an elliptical shape would almost be as easy as their trapezoidal one.

I'm planning on building it out of laminated timber, 80mm finished width then shaped, with 12mm pins in some sort of bushing (any ideas?) so it can take a bit of a wack. I'd probably put a layer of fibreglass on top and a few coats of polyurethane on top of that.

The pintles, gudgeon and whatever look like they'd have to be fabricated out of 3 or 5mm stainless as what's available off the shelf looks to be too small.

I currently thinking of 15 - 20% (45-60mm, bit more than the Scanmar emergency rudder) of area to be ahead of the turning axis to try to cut down on the force needed to turn it though I did see one reference that suggested that this might increase the probability of the rudder stalling.

It'd most likely end up 'round 2.5m in length in one solid piece so it'd have to be stored on deck.

[barnakiel]

If the design is so that it can swing 360 degs you can leave it without locking amidships.

b.

[Jim Cate]

G'Day Bora,

If you are gonna go to all that trouble, why not put a trim tab on the aux rudder and drive that either with a small a/p, or better, with a horizontal axis wind vane?

When I was outfitting Insatiable I for cruising many years ago the budget was limited, and I built my own aux rudder vane system. It cribbed the push-pull cable drive for the trim tab from the Autohelm vane (now marketed by Scanmar). The rudder was built much as you are proposing, the trim tab hung in little teflon bushings, and the whole thing cost less than 300$ for materials (this in 1985). The vane drove the boat whenever at sea, and sometimes when coastal/daysailing, and had over 50K miles to its credit when we sold the boat. I really miss it!

So, have a look at Scanmar's website and consider the possibilities.

I'd be happy to answer any specific queries.

Cheers,

Jim and Ann s/v Insatiable II lying Michaelmas Cay, Qld Oz

[Boracay]

Jim,
I had a look at the Scanmar site as you suggested and there is much there that I can use.
In particular their cable system would be the easiest way to control a trim tab from an autopilot.
The only difficulty that I envisage would be working out what to order. Are they easy to approach or do they really want one to buy a complete system?
At the moment I'm still tempted to build a solid auxiliary rudder and upgrade until it works.

[hpeer]

You may want to look for a book by "John Belcher." He shows how to build a aux trim tab vane. The PO of my boat built one and it works fine. And can be used as an axillary rudder and could be driven by a tiller pilot.

Amazon.com: Wind-Vane Self-Steering (9780877421580): Bill Belcher: Books