Hickman Sea Sled Information

Like this:
Lorne Campbell Design : Sea Sled Dive Tender http://www.lornecampbelldesign.com/boat-commercial-military-SeaSled.htm

I vaguely remember seeing this build thread:
https://www.community.boatbuildercentral.com/forum/viewtopic.php?t=15124

"This is Jacques HS18 scaled down. A variant of the TX18."
I like what he did with the bow box.
If nothing else, scroll through the pictures.

 

You're right about the "classical" sled, with its flat bottom aft; it won't work with jet(s) due to ventilation. We have used an inlet collar, protruding about 50 mm below the bottom on v-bottom jet boats to reduce the inhalation of soft saltwater ice, but it comes with a slight reduction of jet efficiency. I imagine that this trick could work reasonably well on a sled as well.

We also have used a central pod for single jet in asymmetrical cats, again with an efficiency reduction. In those cases this reduction was more than compensated for by the total avoidance of propeller and drive train damage in commercial coastal water operation. This arrangement would certainly work in a negative deadrise hull.

The reason for the efficiency loss is that normally, the jet inlet swallows a portion of the boundary layer, which is fluid that has been "brought up to boat speed", ie it has zero speed relative to the hull. With the collar, this "pre-energized" fluid cannot be used for propulsion, hence the loss. But, as always this loss has to be weighed in when considering the SOR.

The non-tripping chines are too narrow for good inlet conditions, but twin jets far to the sides of a bottom with, say 12 to 15 degrees negative rise would be quite possible.

 

Extremely informative @baeckmo , as always. Thank you.

I thought as much re air ingestion, and the chine width, but
guessing<knowing

 

@baeckmo
Interesting too, that boundary layer momentum recovery makes a noticeable difference to drive efficiency. I was well aware of this in aircraft, from my studies in those fields, but had not connected the dots for jet drives. For long displacement vessels, the efficiency gains would be extremely significant.

 

Smaller jets, ( the types normally driven by V8s- not seadoo style 6 inch units) will have issues dealing with the debris in your west coast waters. Kelp and small pieces of wood ingested can cause problems. Of course you can install a handhole extension to be able to open the jet intake and remove the junk but I have seen kelp wrapped around shafts which pretty well need to be cut off the shaft.
Some pumps will handle passing reasonably larger pieces of wood, say an inch in cross section but if too long, they can get almost permanently lodged in the stators. Berkeley and American Turbine would be the worst but the Hamiltons, like the
212 and the discontinued 773, will pass a considerable amount of stuff. BUT not kelp strings.
The last position that you want to be in is in high waves with the jet intake open while you are trying to clean out the intake.

We were up on a river in northern BC one year and a guy had an 18 foot jet with a Merc Sportjet and he could not get on step to get out of a hole and back into the shallow river. He eventually had to run the boat over a log, part way, that he placed on the beach to enable access to the intake and impellor of the pump. He basically removed the back end of the pump and took out a piece of willow branch, about 2 feet long and 1/2 inch in diameter. That is all it took to render the jet inoperative.

Fwiw

 

Jets are really niche items down in our size range. Really expensive, really vulnerable, relatively poor performers power to weight vs speed. But ultimate shower draft installations.

 

@Barry,
We don't see many issues with jet drives here.
Bull kelp (one of the fastest growing plants in the world) is the biggest issue.
I've seen it, literally, cut out of housings.
It's like when there's too much stuff in the kitchen blender...
nothing happens accept a bunch of noise.
We see mostly Hamiltons around here.

 

Check out the wake on this boat!

 

That (lack of) wake is pretty impressive!
However it would have been nice if they could have filmed the Sled from broadside as well, rather than just a futile attempt at chasing her, and not succeeding.

I had the video on 'full screen', but the Sled was still just a tiny blob in the distance. The camera boat was moving about quite a bit (although the lady in the bow was still managing to film with her camera ok) and I thought it looked like the Sled was pitching a bit?

 

Yeah, certainly the cinematography left much to be desired. I saw the same things: no wake to speak of. No bow wave to climb over to get on plane. When the sled was a tiny blob in the distance, it might possibly have been pitching a bit, although not enough to slow it down. Just walked away from the film boat.

 

Viper Sea Sled https://books.google.ca/books?id=xhsxAQAAMAAJ&pg=PA18&lpg=PA18&dq=are+sea+sleds+dangerous&source=bl&ots=WF1t27kArH&sig=ACfU3U3hE2IMmzBKawdof1aWqPCFLQaqtw&hl=en&sa=X&ved=2ahUKEwidw8KIj4T6AhWwIzQIHT56BxwQ6AF6BAgjEAM#v=onepage&q=are%20sea%20sleds%20dangerous&f=false

Motorboating - ND https://books.google.ca/books?id=4PI1AQAAMAAJ&pg=RA1-PA113&lpg=RA1-PA113&dq=are+sea+sleds+dangerous&source=bl&ots=vpeKmTaO7e&sig=ACfU3U28Q8lnQQr8iMHQn4A4Jw4cR2PNyw&hl=en&sa=X&ved=2ahUKEwidw8KIj4T6AhWwIzQIHT56BxwQ6AF6BAghEAM#v=onepage&q=are%20sea%20sleds%20dangerous&f=false

It's a Bird! It's a Plane! No, It's a Minesweeper! (Published 1972) https://www.nytimes.com/1972/04/16/archives/its-a-bird-its-a-plane-no-its-a-minesweeper.html



EagleSpeak: Sunday Ship History: Hickman's Sea Sleds https://www.eaglespeak.us/2008/09/sunday-ship-history-hickmans-sea-sleds.html

Some gold from Bluebell's research.

 

A new article from Feb 2023
https://www.soundingsonline.com/boats/hickman-sea-sled

 

I neber get tired of hearing about Miss Lakeside.

 

I don't recall seeing all the text when scrolling down on this:
EZ Build HICKMAN TYPE SEA SLED HOME BUILT HULL DESIGN BOAT PLAN 31 new | eBay https://www.ebay.com/itm/255739825738

 

A true believer. At least in the power of the hard sell.