The PT Boat Forum

» Forum Category: PT Boats of WWII

» Forum Name: PT Boats - General

» Topic: Hickman Sea Sled

Do you mean this one? On EBAY it is currently going for between $41.00(missing windshield and without box) and $349.00(mint)!
Take care,
P.S. Seriously, a lot came up when I googled it, but mostly pleasure craft. Only mention of military is purchases made after World War One, not World War Two.


Posted By: TED WALTHER | Posted on: May 14, 2016 - 7:21am
Total Posts: 2919 | Joined: Oct 16, 2006 - 7:42am

Thanks Ted LOL! Yeah, that and the actual diver one's being peddled on Youtube seem to be a common search hit.

Concerning the actual Hickman Sea Sleds, Mystic Seaport has some material including correspondence from Hickman to the Army and Navy during WW2. My fascination from a PT Boat perspective are his Motor Torpedo Boats he built during WW1 (41' and 54') and the sheer number of these sleds used very successfully by both the Navy and Army as crash boats, and seaplane retrieval tenders).

Previously (in March this year) I found a folder on Hickman Sea Sleds in the ELCO records at the Sub Museum in Groton. It was this file that got me looking into the Sea Sled and def supports Hickman's claim that ELCO was specifically targeting him. This was the only folder I found in the entire ELCO collection that contained material on a non-ELCO related company....

And lastly, the fact that a WW1 designed craft was able to launch actual manned aircraft using just the boat's speed, as well as numerous other patented designs kind of places Hickmant on a whole other playing field, in my opinion.

Sea Sled Image

This photo of the Caproni Bomber on the 55' Sea Sled is pretty cool. During the test, the bomber failed to launch due to a malfunction in the release mechanism. Later in March 1919, a USN Float Jenny N-9 (with wheels) was successfully launched, and somewhere there might still be an actual video of this particular test.

I'm currently working on a 1/48 scale build of the C-378, the 54' MTB built in 1918. I've added the 21 torpedo tube (bow mounted) and will include a Hotchkiss 3 pounder as Hickman originally designed. As far as I can find out, the actual C-378 never received it's torpedo setup (had just the simulated weight forward) and did not carry any gun armament. The government changed the four engines from aluminum to bronze just to make things interesting and mess around with the boats trim (a standard sort of reoccurring theme between Hickman and the US government carried into WW2). It did conduct a full set of trials and was tested specifically by Henry Mustin (Naval Aviator #11) during the 55' Sea Sled proposal to launch bomber size aircraft against Germany.

Happy Rabbit Hole!


Posted By: Andy Small | Posted on: May 14, 2016 - 9:32am
Total Posts: 223 | Joined: Nov 20, 2013 - 9:04pm

Is this Hickman's 55 foot "Aircraft Carrier"? I read this thing was clocked at 48 knots. That is awesome speed for late/post World War One!
The limited range of the airplanes of the era killed the program. Very interesting!
Take care,
P.S. I never even heard of this before. The only sled I know about is the
Fulton High Speed Multi Swimmer Pick Up System:

Posted By: TED WALTHER | Posted on: May 14, 2016 - 5:22pm
Total Posts: 2919 | Joined: Oct 16, 2006 - 7:42am

Yes on the Aircraft Carrier. Actually the war ending killed the program. The plan was to launch the aircraft from the Zuiderzee (which was still open to the North Sea), giving the aircraft an additional 150 NM range and thus opening up previously protected Northern German targets to air attack.

The Photo is one of the two 55' Sea Sleds built for launching aircraft that were completed just before the end of the war. It was a hybrid of his original design and incorporated sponsons with flared bottoms and small order to provide additional width to support the large multi-engine bombers as well as improved turning capability of the sleds. Hickman fully understood that the addition of the sponsons would degrade the boat's seakeeping in heavy seas, but you would only be launching these large aircraft in the protected waters of the Zuiderzee (assuming the Dutch would let you).

Posted By: Andy Small | Posted on: May 14, 2016 - 7:44pm
Total Posts: 223 | Joined: Nov 20, 2013 - 9:04pm

 photo Hickman Motor Torpedo Boat Surface Piercing Props and Side Rudder_zpskunv3eof.jpg

Stern of 1/48 Scale Hickman Sea Sled Motor Torpedo Boat.

Posted By: Andy Small | Posted on: Jun 14, 2016 - 3:31pm
Total Posts: 223 | Joined: Nov 20, 2013 - 9:04pm


Below is the corresponding legend for the numbers. Sorry for the dark paint job which blots out the details. I really like the earlier dark paint job used by the steam torpedo boats, so I used it instead of the more likely dark gray.

1-Four surface piercing props (another Hickman patent), two left, two right. These props are usually about 20% larger than regular props, so the whole transom is a vicious meat grinder.
2-Side rudder. Only the rudder in the turn is activated (sort of like a canoe paddle or steering board). The other just trails against the vessel. The combination of the side rudders and the transom mounted surface piercing props meant the draft on this 54 footer was just under 3 feet max and usually less since it nicely went up on plane. A comparable regular hard chine boat of this sized usually about 5.5 feet in comparison.
3-The four lift eyes that were an integral part of the internal light commercial steel truss framing. The boats sides with trusses in between were the main supports. All main weights from weapons to engines were directly supported by this steel frame. The skin of the boat was oak under framing with mahogany planking. You could lift a fully loaded (fuel, weapons and people) from a mother vessel directly into the water. I concept very similar to what is now used with RIBs and Naval vessels.
4-Bow launched single torpedo. Original proposal was an 18” Mark VII torpedo. Hickman specifically designed the 1918 C378 for the larger 21” Mark VIII torpedo. This would have moved the tubes breech to about where the gun mount is located (item 5).
5-Base of the Hotchkiss 47mm 3 Pounder. This is the same gun mounted on larger ships to defend against torpedo boat threat. The Navy proposal called for just a 1 pounder (37mm).
6-The helm with 4 throttles. The steering was similar to an automobile with the helmsman seated.
7-Engine compartment for four 350 HP engines that had to be built by Hickman. Navy required these to be bronze instead of the spec’d aluminum engines. This added a great deal of unnecessary weight aft.
8-This is a best guess. Some information on the original proposal suggests just an access hatch, but information on C378 suggest this area was an open, and more typical seated crew station.

Despite being overloaded by the bronze engines, the fully loaded C378 had a top speed of 37 knots. During one run in an winter storm with 12-14 foot seas, C378 averaged 34.5 knots which is a speed faster than a destroyer through the same seas. The weight per horsepower at full speed is 40 pounds. The Sea Sled hull design with a somewhat flat trim to about 1 maybe 2 degrees, surface piercing props (always an even number so either 2 or 4) and side rudders were all part of the total package. Unlike normal hard chine boats, spray and bow wake was pretty much non-existent. The shape of the sled made the hull a natural dampening force. One Army observer during WW1 (Army bought these as crash boats) noted that when the sled hit a huge wave and launched the boat up about 30 degrees, he was expecting the boat to come slamming down hard, but instead the boat gradually returned to its previous stable trim. The boats made before and during WW1 did not have the beveled chine, so in high speed hard turns, the Sea Sled had a tendency to “trip”. It was during the design of the follow on aircraft carrying 55 foot sea sled that Hickman came up with the beveled and stepped chine which he submitted for patent in 1922. This really helped with turns.

Posted By: Andy Small | Posted on: Jun 14, 2016 - 3:43pm
Total Posts: 223 | Joined: Nov 20, 2013 - 9:04pm

Great post, Andy.....


Posted By: Will Day | Posted on: Jun 14, 2016 - 10:22pm
Total Posts: 1936 | Joined: Oct 8, 2006 - 4:19pm


Here's the only photo I could locate showing C378 on trials in 1918. It's from a Motorrboating magazine advertisement (sorry about the Moire marks - couldn't make them go away without totally destroying the image).

The Sea Sled is up on plane at high speed. Notice the lack of bow spray. It's also a bit lower in the stern most probably due to the heavy bronze engines. If you look at photos of the 55 foot aircraft launching version (which had lighter weight aluminum engines), the high speed profile is almost flat, which is also the profile you'll see on racing sea sleds). This flat profile is important since as the angle increases, the tendency for the boat to ride rougher increases. The Admiralty, who bought some of the smaller all wood Sea Sleds during WW1, complained about them. From what I can find out, the Royal Navy was freaked out about the way the boats sat idle in the water so they loaded them heavily in the stern to raise the bow. This messed severely with surface piercing props performance and increased the pounding forces by not allowing the sled to slice through the water. This type of tinkering seems to be a recurring theme when issues came up concerning the sled. The sled was quite the machine, but it was a total Hickman package: hull design, weight distribution, surface props, side rudders, and later beveled chine. Hickman used each element of the design to support the others, but when the government insisted on changes that greatly affected either one component or the overall design, bad things happened. These boats had tremendous weight carrying capability, and it was said that weight improved it's rough sea performance, but the weight had to be properly distributed for the best performance.

....and back to the photo, the helm of C378 is forward of the engine housing with what looks like a metal hand rail running from port to starboard just behind the helmsman. The search light is on the forward deck and it does not look like there is adequate room for a 3 pounder Hotchkiss. Usually if a boat is armed, the search light is aft of the gun and mounted higher. You can just make out an old style anchor on the starboard foredeck and the two men aft look to be standing in a cockpit just aft of the engine house. Also, no apparent ventilators, which suggest an engine compartment with large folding hatch covers to allow complete access to the engines. This is a common design on his civilian versions of the sea sled.

The version I decided to build is more based almost entirely on Hickman's original 1914 proposal (complete with ventilators and gun mount), but with some acknowledgement of information I obtained from the photograph.

The whole bow launched torpedo and information stating C378 designed specifically for the MkVIII torpedo is a head scratcher for me. Due to the setup, the MkVIII would need to be loaded fins first, so probably it was envisioned that these boats would be on deck of the mother ship so the torpedoes could be loaded using the standard torpedo wheel carts used on the old Battleships and Cruisers. The breach mechanism and firing of the torpedoes is also a puzzle. Maybe there was a deep cockpit area forward of the helm with the torpedo man standing on this lower deck and just able to look over foredeck to see the target. Another shipmate would operate the search light. Some of the 1914 information suggests this setup for the non-gun version of the boat. Probably a better torpedo setup would have been the one used by the WW1 MAS boats with two smaller 18 torpedoes launched from the sides amidships. Probably the increased stability of the sea sled would have also worked well for the boat davit torpedo rack that Melville came up with in 1941. Just some thoughts. I love this stuff!!!

Posted By: Andy Small | Posted on: Jun 15, 2016 - 3:58am
Total Posts: 223 | Joined: Nov 20, 2013 - 9:04pm

VERY interesting! It is amazing, while this boat was not officially accepted into Navy service, I can see design features on this craft that are on craft like the Medium SEAL Support Craft(MSSC) which was operated by Mobile Support Teams, MST 1, MST 2, and MST 3 in Vietnam. Then the follow on Mini ATC(Armored Troop Carrier),engine set up was twin 8V92TA and jet drives. These boats were handed down to SBU 22/24/11 and up until the 1990's in NSW. I can also see design features on this boat that are on the current Special Operations Craft-Riverine(SOCR). Even though both of these boats are 36' long, both of these boats ride as your research says C378 does, smooth settling ride in heavy seas and they also trip or skid in high speed turns. the MSSC was a outdrive set up with twin 427 Chevrolet engines. The SOCR is jet drive with twin 440hp Yanmar diesels.
Nice work!
Take care,

Posted By: TED WALTHER | Posted on: Jun 15, 2016 - 9:07am
Total Posts: 2919 | Joined: Oct 16, 2006 - 7:42am

Nice model Andy and thank you for the history. It sounds like Hickman was an innovative man.

Posted By: Jeff D | Posted on: Jun 15, 2016 - 12:45pm
Total Posts: 1977 | Joined: Dec 21, 2006 - 1:30am

Hickman continued to be innovative. Once WW2 started, I can easily understand why the Soviets wanted to immediately purchase 80 of these as torpedo boats. Having the entire internal framing mass produced by US Steel with a marine plywood skin meant the materials for the entire order could have been shipped in a few vessels and assembled quickly on location by relatively unskilled labor. Of course the supply of Packard engines and armament would have still been a hold up, but I'm sure this order would have been completed much faster and at less cost than what unfolded with the ELCO, Higgins and Vosper orders.

As for the estimated cost and performance of the proposed Sea Sled PT Boat, computations seem to indicate the boat hull's cost at about half what a traditional PT Boat cost. At 78 feet, breadth 16.5 feet, draft 4 feet, the fully loaded boat top speed (with its four Packards including 4000 gal of fuel), was estimated to be in the 50-60 knots range, with speeds in heavy seas estimated at 35 knots and long range cruising speed around 30 knots. Like the WW1 boat, this vessel could have been hoisted fully loaded by the four lift rings. These very roomy vessels would have provided a very stable platform for a forward firing 40mm gun mount and ample deck space (and hull support for all the assorted weapons. All a very interesting what could have been scenario if Hickman had been allowed to compete.

Posted By: Andy Small | Posted on: Jun 15, 2016 - 7:27pm
Total Posts: 223 | Joined: Nov 20, 2013 - 9:04pm

Here is the smaller version being tested as an Air Sea Rescue boat Feb 1945 Rockland Maine,


Take care,

Posted By: TED WALTHER | Posted on: Jun 16, 2016 - 10:44am
Total Posts: 2919 | Joined: Oct 16, 2006 - 7:42am


Posted By: Jerry Gilmartin | Posted on: Jun 16, 2016 - 4:13pm
Total Posts: 1258 | Joined: Oct 8, 2006 - 11:16pm

Wow Ted! Wild 80ft Elco spotted!
Did you notice that in your film at time stamp 7:00 all the way to 9:20 they show a closeup of Elco PT486 fully armed rescuing the test dummy in the life raft? It has all the weapons it was equipped with. This was filmed in Feb of 1945 so I guess that makes sense. Good find!

Jerry Gilmartin
PT658 Crewman
Portland OR

Posted By: Jerry Gilmartin | Posted on: Jun 16, 2016 - 4:13pm
Total Posts: 1258 | Joined: Oct 8, 2006 - 11:16pm

Yes, and here is some more proof PT 486 and PT 452 were sent up TAD to Rockland Maine for these tests.

Take care,

Posted By: TED WALTHER | Posted on: Jun 17, 2016 - 10:41am
Total Posts: 2919 | Joined: Oct 16, 2006 - 7:42am

Here are some updated photos of my 1/48 scale project. I added the 47mm Hotchkiss and anchor. The gun was fun to build and adds a wicked steam punk look to the sea sled. Used my laser to cut laserboard and basswood and filed down aluminum tubing to maker the barrel and some brass rod for one of the handles.

Been trying to figure out how the ready ammo was stored on a bouncing boat. The Russians stored their small 47mm ammo boxes within the gun mount stand just stacked on the deck of their larger vessels.

Even though it's not completely done, I've decided to bring the model to display at Mystic Seaport this coming weekend ( the Annual Wooden Boat Show). Sea Sleds were built in Mystic during the 20s and 30s and the seaport has four small sea sleds in their collection (three 13' and one 16'). The 16' is cool to see since it has the beveled-stepped chine (built in the mid 20s).


Posted By: Andy Small | Posted on: Jun 19, 2016 - 9:33am
Total Posts: 223 | Joined: Nov 20, 2013 - 9:04pm

Interesting connection to TWE and MGM on that page you put up Ted, have not seen that before thanks,

Posted By: David Buck | Posted on: Jun 19, 2016 - 6:40pm
Total Posts: 332 | Joined: May 4, 2008 - 2:59am

Great plug for the Fold3 website. I've spent many, many enjoyable hours reading through all the war diary and after action reports they have made available on their site. Fantastic online resource. Like reading an unedited At Close Quarters with an unpublished Volume II, and all from the comfort of home.

- Andy

Posted By: Andy Small | Posted on: Jun 19, 2016 - 7:41pm
Total Posts: 223 | Joined: Nov 20, 2013 - 9:04pm

Found some interesting information on sea sleds including a proposal from Sep 1936 for a 57 ft sea sled six engine motor torpedo boat with three 18 torpedoes.

Also, I believe I uncovered why there seems to be such extreme variation with the reported ability of the sea sled to handle rough seas. On the one hand we have significant designers, sea sled owners such as the owner of the magazine MotorBoating, and boat racers strongly supporting the sea keeping of the sea sled design, but we then have instances of the Navy saying how horrible they are. Two sea sleds that were tested and specifically evaluated by the Navy and mentioned as the reason not to buy sea sleds are the 32' crash boat in Pensacola 1916 and the 45' crash boat in Hampton, VA in 1935-6. Both of these vessels had extremely high beam to length ratios, in fact the highest (by a significant factor) from the 40 some models of large sea sleds I've been able to find information on. This would probably mean that the angle in the forward part of the vessels was probably way too shallow and would have had a significant role in increasing the slamming affect in any sort of chop. It seems that Hickman was trying to provide a very stable platform from which to facilitate personnel rescue for these crash boats.

A narrower beam for the sea sled would have increased the hull angle at the point of entry and would have greatly helped the ride, just as this does for V bottom boats. A sea sled the navy was happy with, the C-378 motor torpedo boat that CAPT Mustin evaluated in 1918, had narrower beam, a greater hull angle and was felt to have great sea keeping capability despite the navy insisting on using overweight engines which greatly affected trim. CAPT Mustin employed light weight engines on the aircraft sea sleds C-1558 and C-1559.

Posted By: Andy Small | Posted on: Sep 26, 2016 - 12:10pm
Total Posts: 223 | Joined: Nov 20, 2013 - 9:04pm