Switching to an inboard prop instead of tilt-up outboard?

[Nicholas Scheuer]

Pursuing the idea of the Bukh posted earlier, I'm thinking a ducted prop would be better than one entirely exposed, or shielded memrely by a skeg.

My Shearwater draws only 6-inches with her rudder fin and leeboards swung up, so the big 11" prop on our 9.9 Yamaha-HT is the deepest element, by far. I often get too careless in the shallows, which up in the North Channel tend to be Granite, and bang up the prop. Rather than live with vibration for the reainder of a weel-long cruise, I switch over to a spare prop (one fresh out of the rop repair shop). So I'm thinking that a duct for a fixed prop behind a Bukh would be a good idea for me.

My question is, how much better is a duck having a foil cross-section rather than merely having a straight-walled tube?

Moby Nick

[TerryLL]

How about one of these.

http://www.nstsystems.com/multihulls/PropellerGuard_files/image004.jpg

[Nicholas Scheuer]

That looks like just what I need, TerryLL!

I thught the link provided was for the prop duck, but alas, it's for weaving tools. Nice swebsite! Just last evening we saw an early 19th Centyry Swift made of Wahebone on the Antiques Roadshow.

[TerryLL]

The pic I posted was off Google Images. If you search "prop guards" you'll get lots of hits.

The whalebone swifts are pretty amazing, but the ivory swifts are beyond imagining. I've seen prices approaching 100K. Not bad for a trinket made by a bored whaler in his spare time.

[paladin]

I got a half dozen or so in my collection...along with some Tupalaks, a good collection of Netsukes (pronounced "net ski"), and a few pieces of Sperm whale teeth that I wuz gonna scrimshaw.

[TerryLL]

I got a half dozen or so in my collection....


A half dozen ivory swifts? I gotta see pics!