Hickman Sea Sled Information

[BlueBell]

https://www.thehulltruth.com/boating-forum/889308-project-sea-sled-2.html

 

[DogCavalry]

That's Tony Dignity's boat. We were emailing back and forth when I started my build thread. I'd better send hime some pics...

Edit
RobinT as well. He has that aluminum sea sled shaped main battle tank. Has a pair of 225 optis, iirc.

 

[DogCavalry]

So time for a report based on my own first hand experience.

First the good:
Serenity is an amazingly comfortable ride. I've been using her most days, I drive standing, and there was only one occasion where I needed to use a hand for balance. The government spill response boat is a big drop bow vessel three decks high, and powerful. She went thundering up the arm a few weeks back, the rooster tail behind her was two stories high. When the wake went across me I was rolling, well platforming actually, 45° left and right, much faster than a boat could roll. I held on for a few seconds there, or I'd have been thrown wall to wall a few times.
More typical was Saturday, a gorgeous day with a good stiff breeze that had sailboats flying along nicely. The water was busy, all the rich nobs from the RVYC heading up the arm to their private club in their rich folks power yachts. Their wakes were enough I saw some 50-60' boats getting thrown around uncomfortably. And for the only time, I was passing everyone, because those wakes just didn't matter to us. Well, my coffee cup was sitting on a shelf, and it fell off. I should put in a cup holder. Even the steepest wake felt like a soft "wumph". If I was in our commuter I would have had a very uncomfortable time. Probably hurt my back on some of those landings.
Similarly, last fall we had a big arctic outflow day, and despite the shining sun, I had the water to myself. I thought nothing of it, until people started phoning me as they saw me passing. Two phonecalls and a text conversation. Apparently no one was out because the locals though it was suicide. The text was about how if I got in trouble they could only watch, because their dock was moving so violently they couldn't even set foot on it. That seemed a bit of an exaggeration until I reached my clients' dock... Yeah. I turned around and went home.
So stable, comfortable, controllable.

She can indeed get on the plane under ridiculous conditions. Six months in the water, August to January, no antifouling paint. Beard hanging down, barnacles everywhere there weren't mussels or kelp. And my friend is moving in. He had a two bedroom apartment and a massive book collection. 85 boxes of books and everything else to fill a moving van, all loaded in to Serenity. And she got on the plane. Not fast mind, but planing. 25km/hr or 14 knots is above displacement speed in a 26' boat. That seems more than adequate. Probably would have been much faster without the wheelbarrow full of life encrusted on the bottom. Based on fuel flow, she was probably making about 100hp, or ~75kW.

The square bow is just incredibly useful and practical. I'm not going back. If you have work to do from your boat, it's a gamechanger. Seriously.

Wake is miniscule considering weight, power, and speed. A dramatic difference.

The bad:
Too much wetted surface drag. Coming into the speed range where a comparable V hull is lifting up and getting less and less contact area, Serenity's contact area is more or less constant. That really limits higher speeds. There is much I can do, and will do, but at different speed regimes different kinds of drag dominate and that's a fact. For higher speeds @baeckmo 's hull form with the tunnel carried to the transom would have been better. But the hull was built before I first exchanged a word with him. Next boat will follow his lead.

The aerated water in the tunnel really is a *****. Twin props would have been much better. I've gone through a lot of trouble over that. Be advised.

Neither good nor bad, but noteworthy:
She planes in a wide range of trim. Generally around 3.5° up, like most planing boats, but the other day, with the whole family in the cockpit or on the fore-deck she planed comfortably at 0° trim. We maintained ~40km/hr like that with no issues. Now the apex of the tunnel would have been at 3°, so there was dynamic lift, but it was interesting. A tremendous amount of wetted surface like that. Not good fuel mileage, but if I was doing taxi work, that would have been pure gold.

It's reasonable to say that Hickman's boats were much faster than my boat, because a 26' boat would have been 6' wide. At 60% the contact area, top speed would be higher. A less useful boat though.

Anyway, that's what I know. I hope this information is some compensation for the immense help and support I've received over the last four years. Thanks guys. More information as I accumulate it. Phyfox data soon.

 

[BlueBell]

I think without the correct prop, power trim (on-the-fly) and perhaps even a power jack-plate (as I see recommended on so many Sea Sled builds and plans), and correct boat trim, you'll never know what the single engine is capable of on your boat.

All this wetted surface area is part of what gives the Sea Sled it's unique performance characteristics.
Not sure why you built one only to come to the realization it's not a sound design.
Or is it that you simply have the wrong prop? We may never know at this rate.

 

[DogCavalry]

I have a friend with a roughly comparable V hull. I'll take him for a ride. @Mr Efficiency pointed out some while back that ride comfort is highly subjective. What seems like a reasonable ride to me might strike someone else as unacceptable, so maybe I'm unrealisticly positive about that attribute.

 

[DogCavalry]

TX 18 study plans. Max outboard they recommend is 50hp.

 

[Geno67]

Has anyone mentioned the Laguna Tiger? I think it's probably the best hull layout in modern times even though it was marketed as a flats boat. Main difference is tunnel carried through and all having hydraulic jack plates for very shallow running.

The designer/producer Mike Mills states in one thread on 2coolfishing:

"NEW Laguna Tiger boats with step boxes...

Laguna Tiger 18'6" (in photo)

Mercury Optimax 115 hp

Bob's Low Water pickup

This boat will take off from the position you see in the photo, jack plate at full up. It will also idle in this position for those of you who want to go into really shallow water and not have to push the boat out by hand.

Take any other boat, take off, leave jack plate in take off position and see for yourself how your boat measures up.

Gas mileage tests on this rig: 3 persons on board (270#, 240#, 190#) 2 coolers with ice, all fishing tackle and food for 3. Full tank of fuel, anchor, etc., we ran 71 miles on the GPS unit (average speed = 4100 to 4800 rpm) pulled the boat back to the same gas pump, going the same direction, on the same day, for 71 mile trip, took exactly 7 gallons to refill to the mark made that morning when filling up. That's 10 miles per gallon, any way you figure it.

This is the inverted vee hull, based upon the original Albert Hickman design, but, redesigned for the Laguna by carrying the vee completely through the hull. In 1914 when Hickman first developed the hull there were no outboards and he made the transom area flat-bottomed to carry the extra weight of the engine and transmission.

This is a very honest hull, it is stable, fast, smooth and dry and I would be glad to put it against any hull any one would like to compare it to. Run them both, same time, same water and let's see how they stack up."

And in another, same forum:

"Since I own the Laguna Tiger and built it I thought I might help you out with some facts. The boat is 18' X 8' beam, weighs 520 #, runs 40 mph with 2 people on it. 90 hp Yamaha power. It's all welded aluminum as this is the first one and it would have been much less expensive to build it out of aluminum instead of having to make a plug and then a mold to build in glass. The only other option would be plywood and that would still really be just a plug as far as I am concerned.

I took the boat to Corpus two weeks ago for initial testing, it was really great, much better than expected actually. With a 20 mph SE wind, we, three people, took it into CC Bay, i ran the boat at all possible angles to the waves, even to the point of turning it around at 3500 rpm in a small circle. Resulting in NO pounding and NO spray in the boat. Albert Hickman's #1 claim was always that his "Sea Sleds" never, ever pounded in rough seas. Neither does my version, it is spooky smooth and dry. I took several area Charter Captains riding on it and to a man they said it was the best ride they had ever experienced, bar none.

While the boat that I saw pictured on this site, the TX18, that is a kit boat that has similar vee design, but, it is a flat-bottom-transom design very close to Hickman's original drawings. It will work, but, does not run well in shallow water as the engine will overheat if you try to run shallow. It has no way to feed water up to a raised engine like mine does.

I had several options when thinking about my design, I could either build it flat as Hickman did, put in a tunnel as most S TX flats have, or, get creative and run the inverted vee design completely though the hull and use that as a tunnel. i decided on number three as it made the boat more unique and I liked to idea of extending the inverted vee through to try and capture even more of the air-cushion ride. It worked..."

 

[fallguy]

I'd call that a catamaran.

 

[Geno67]

I would as well at first glance. The hull at the transom is an inverted v. Straight lines from the centerline to the hullsides. The designer/builder also stated it's a Hickman derived inverted v design.

 

[baeckmo]

I'd call that a catamaran.

And in that, you'd be wrong. The essense of a catamaran hull is that the tunnel roof should not be continuously wetted, but the inverted vee is, from a hydrodynamic view, a monohull, since the whole bottom width is load carrying.

 

[fallguy]

And in that, you'd be wrong. The essense of a catamaran hull is that the tunnel roof should not be continuously wetted, but the inverted vee is, from a hydrodynamic view, a monohull, since the whole bottom width is load carrying.

But the inverted portion of this boat does not touch the water or does it? If anything it would only be splashes, no? What did I miss?

 

[Geno67]

It does touch the water at rest and underway and that's the difference.

I was planning on building a cat but I think I want to build one of these finicky creatures now. I have TX18 plans but I want high sides like a normal craft instead of the low sides and I want to carry the v completely through the hull at least some like the tiger. I don't have any idea how to modify the plans I have to achieve those goals. I wonder if any of the folks here would be willing to do so for a reasonable fee? The whole reason I'm building is that cat hulls command a crazy premium and are well outside my meager budget and finding one with a standard helm layout is impossible. Of the very few I've found so far within my budget, I would have to replace the stringers and transom and redo the helm from center console to dual. I might as well build something I want instead.

 

[baeckmo]

But the inverted portion of this boat does not touch the water or does it? If anything it would only be splashes, no? What did I miss?

That's not the point. I wrote "the whole bottom width is load carrying". This refers to the hull moving through the water, which is what a boat is supposed to do.

 

[fallguy]

That's not the point. I wrote "the whole bottom width is load carrying". This refers to the hull moving through the water, which is what a boat is supposed to do.

I did not understand that it was behaving differently than a catamaran bridgedeck.

---> I was not attempting to make any points; despite the style of my query.

It does touch the water at rest and underway and that's the difference.

thanks, I was not clear on this bit

 

[Geno67]

Part 1 of a plan to do testing of a sled against a cat and a foil. Sadly, I could not find part 2.

There is a first hand account from the author in 1958 of having driven a sled in nasty seas and it being as dry and comfortable as a lounge chair at his home.

https://www.foils.org/wp-content/uploads/2018/01/Argosy1958Feb.pdf