Boeing began looking into hydrofoil boats in the early 1960s.  A waterjet powered boat with fully submerged hydrofoils was first tested in a 20 ft runabout called the Little Squirt.



This evolved into a series of boats - see the family tree at the bottom of this page.  In the early to mid-1970s, Boeing decided to expand into the passenger boat business.   Like so many of their "diversification" endeavors over the years, it proved relatively short-lived, unsuccessful, - and very costly.  They cleared off a section of the Renton plant and began building some large high-tech speedy hydrofoil boats, right next to the airplanes.  So - what could go wrong???

All six PHM's flying in formation

The Jetfoils could carry 200-400 passengers, and were powered by two Allison 501-D13 engines - the same engines that were used on the Lockheed Electra, P-3 Orion, and C-130; also the Grumman E-2A Hawkeye and Convair 580.

They, in turn powered, through large gearboxes, two large Rocketdyne water pumps - derived from the Saturn S1C F-1 rocket engines used on the Apollo moon rocket.  They pumped an immense volume of water through two water jets that had nozzles that could direct the flow left or right, and could also reverse.  The Jetfoil had no propellers (although it did have a Bow Thruster.)

Three of the first four boats went to Hawaii to "fly" between the Islands.  An interesting wrinkle in this was that the "customer" was an outfit called Pacific Sea Transportation that operated under the name Seaflite.  Seaflite was a joint 50/50 venture between Boeing and Ling Temco Vought (LTV), meaning that Boeing was setting up shop in direct competition with one of their customers - Aloha Airlines.  That didn't sit too well with Aloha, and as the Rep assigned to both of them, made my life a little "interesting."

In the end, Seaflite didn't last too long - about 3 years, so Aloha didn't have much to worry about in the end.  But it did cost them (and Hawaiian Airlines) needed revenue.  A "Back of the Envelope" calculation of the financials should have shown the problem before the starting gun went off.  Aloha's 737s seated about 115 pax and could make a round-trip to Maui in one hour.  Seaflite's Jetfoil seated about 230 pax and took something over two hours to get from Honolulu to Maui.  Do the math and you can see the boat had half the productivity compared to the airplane.  Since the boat and the airplane cost about the same, and the ticket prices were similar - Q.E.D.  an expensive way to go broke fast.  Which Seaflite ultimately did.  Their boats all wound up going to the operator in Hong Kong.

 Unloading  a Jetfoil in Honolulu after transit from Seattle.


After the Jetfoil was raised off the Matson deck....
...the ship was shifted out from under to an adjacent dock.





A good view of the bow thruster and the small 5 foot draft



Then the Jetfoil was lowered into the water.

---

My "New" World


USCG Cutter 717 - the Mellon - at Sand Island base in Honolulu

Time to head out



Departing the Honolulu Terminal







Take-off would be out the Channel






Passing Waikiki





Diamond Head

The boat featured two fully submersed hydrofoil lifting surfaces attached to stainless steel struts.  They were controlled by powered trailing edge flight controls, similar to elevons, that were controlled by sophisticated flight control computers.  They were superior to the more common "surface-piercing" hydrofoils seen in many places, including Italy and Russia.  But, unlike the surface-piercing hydrofoils, they are not inherently stable and depend on a sophisticated flight control system (FBW) to maneuver and stay foil borne.

Becoming foil borne entailed a take-off run similar to a seaplane or flying boat.  Once foil borne, the boat could be controlled to fly at a set distance above the water surface using something akin to radar altimeters.  Up to about an 8 foot sea state, the boat could maintain a smooth and stable ride.  Above that up to about 15 foot, the autopilot could be switched to a Contour Mode, where it would maintain a fixed height above the sea surface but would no longer be level.  Instead, it would follow the profile of the approaching seas.  This was a less smooth ride, but still much smoother than a boat pounding into oncoming seas on its hull.  The boat could try and maintain being foil borne in higher seas - perhaps 35 feet - but the higher the seas, the more difficult it was to stay foil borne. 

The Boeing Jetfoil was a technological marvel and offered much.  When the water was smooth and everything was working just right, it gave an amazing, smooth ride.

One thing I remember clearly was riding in the engine room while we did maintenance trials and adjustments.  The noise was the loudest I ever remember - deafening even with protective earmuffs on.  Now, in my dotage, I have lost a good deal of my hearing and wonder whether those engine room rides might have been the cause???

I remember going on a wedding charter one day to Maui.  The whole wedding ceremony, bride and groom, preacher, cake and wedding party were aboard the boat and the ceremony was performed enroute.

On another occasion, we were doing a shakedown trip, after maintenance, foil borne south of Oahu, and called Pearl Harbor Control and asked if we could enter Pearl and circumnavigate Ford Island - foil borne (at 50 kts.)  They said OK, so we did, going around counterclockwise.  There was no Ford Island Bridge in those days, so we could could circle the island.  While foil borne, the Jetfoil left almost no wake.  I often think of those days and wish I had the photo and video gear we have today so I could have better recorded some of this stuff.

We passed the Arizona Memorial and then passed the Battleship USS Utah (BB-31) at the north end of Ford Island.  It was also left in place after Dec. 7, and was half upside down, bottoms up.  She's still there, lying on her side.  Four men were rescued by cutting holes in the bottom, but 58 men remain still aboard.  To date, 17 surviving members of her crew have chosen to be interred in the wreck along with their shipmates.  


With such nice attributes, it didn't succeed in Hawaii.  How come?  There are a number of reasons.

One I mentioned earlier - the financials just didn't pencil out when compared to an airplane.  Not even close.

Another reason were a lot of teething and in-service mechanical problems that severely impacted reliability.  The boats had to be sent back to Boeing several times to get repaired and upgraded.  A very expensive proposition.

But the main reason - IMHO - was that it was the wrong product in the wrong place.

It was really designed for inland waters - such as e.g. Puget Sound; maybe going from Seattle to Victoria.

The open ocean waters were very, very different.


Wind and waves were too much for the boat in Hawaii.
They pounded the hell out of the boat, and its structure was too fragile.
The hull, built from welded aluminum plate, developed cracks almost daily.
The stainless steel struts and foils were no better.
The welders were out every night welding up cracks.
There were welds on the welds.

---

The system of vertical struts and horizontal hydrofoils allows the Jetfoil to fly smoothly in moderate seas.  (Some of this is by memory, so send me a note if I stray.)  I recall you could fly the boat smoothly and level in seas up to about 8 feet.  This would be considered Sea State 4, "Moderate", and was common on, say, the Kauai Channel.



Between  8 and 15 feet, (Sea State 5 - "Rough"), you would switch to Contour Mode.  Using height sensors, the boat would maintain a constant height above the water surface.  No longer Level, it would follow the Profile of approaching seas.  The result while no longer straight and level, was much smoother than a hull borne vessel pounding through rough water.

Two challenging channels exist in Hawaii - 1) the Kauai Channel between Kauai and Oahu, and the Alenuihaha Channel between Maui and the Big Island of Hawaii.  The latter can be especially nasty - it sits between between two huge mountains - Haleakala on the eastern end of Maui is an extinct volcano rising over 10,000 feet.  Mauna Kea and Mauna Loa on the Big Island are the two biggest mountains in the world - rising almost 14,000 ft above sea level (but rising over 32,000 ft from their bases on the sea floor.)


The NE Trade Winds blow 11 months of the year and the mountains create a huge venturi accelerating the winds (with a similar water venturi beneath the waves.)  The result can be rough seas!

One day we were doing a Kauai trip, crossing the Kauai Channel.  It's about 100 NM (Nautical Miles) across from Kauai to Oahu (Honolulu.)  The boat docked in Nawiliwili Harbor near Lihue on Kauai.  In good weather, the trip can take about 2.5 - 3.0 hours.

We left HNL about 1300 and arrived Kauai about 1600.  The sea was not friendly that day, but the Captain skillfully kept it foil borne for the whole trip.  I remember it vividly to this day.  Driving a boat in heavy seas is not just a challenge, but can be one of the most horrifying experiences imaginable - made worse by the high cruising speed of the Jetfoil.  Watching from the wheelhouse - and especially from the wing of the Bridge, you crest a wave and look down into a bottomless black pit where the ocean appears to drop into the center of the Earth.  Then the boat pitches down and slides down the backside of the sea.  As you approach the trough, the imagery reverses and you see the full scope of the following sea.  It looks like a 5 or 6 story apartment house of solid water rapidly approaching - the image made all the worse before you hit the trough because the boat is still pitched downwards.  As you hit the trough, the boat then rapidly pitches up to climb the face of the following sea.

The first - rare but not unheard of - is burying the nose into the face of the following sea just past the trough.  This can mean taking "green water" clear over the top of the boat.  When that happens, sea water can pour down the engine exhaust stacks, killing the engines and quickly sending the boat back on to the hull.  Getting the engines restarted can be a lengthy purging operation.  This event has happened several times, once off the West entrance to the Straight of Juan de Fuca during Boeing testing.  The best solution is to avoid high sea states!  At least while foil borne.

The second problem is not so rare and we encountered it a number of times.  Flying the boat during heavy seas can occasionally cause the waterjet inlet to uncover.  Most often, this can occur when the boat crests a wave and begins to pitch down the back side of the sea.  When this happens, the waterjet system takes in a slug of air.  When the air hits the water jet pumps, they overspeed, along with their drive train including the engines.  Protective sensors and devices sense the overspeed and immediately shut down the engines to protect the propulsion system from damage.  But, again, the boat immediately drops on to the hull.

The Jetfoil is a vessel with a huge Freeboard (area above the waterline) and almost no Draft (5 feet) - the area below the waterline.  With the boat on the hull and no propulsion power, it's like a cork in the ocean, subject to the full forces of wind and sea.  It's not pretty!

We left Kauai about 5:00-6:00 PM (1700-1800hrs), successfully took off and headed across the Channel for Honolulu.  We had a full load of pax.  About half way across, it got dark and observing the seas had become very difficult.  Then we had an inlet uncover event and the engines shut down.  The boat fell onto the hull.  Besides the two Allison propulsion gas turbines, the boat was equipped with two diesel engines that provided utilities (electric and hydraulic power, and air conditioning), so the boat wasn't sitting in total darkness and helpless.

There is a Handbook procedure for this event; carefully going through the cool-down, purge and re-start procedure could take 10-15 minutes.  While the wheelhouse crew was busy, the passengers were left in the pitching and rolling boat while darkness prevented observation of any horizon.  We were (literally) in the middle of the ocean, well out of sight of any land.  Some of the pax started getting sick.  The sight and smell of sick people promotes other people getting sick.  Soon, the entire boat load of 230 pax were sick.  I looked through the wheelhouse bulkhead door window and could see a sea of vomit sloshing across the upper deck and cascading in a waterfall down the stairway to the lower deck.  I kept the door closed.

With the engines back running, we had two choices - attempt to get foil borne again, or proceed on the hull.  The boat speed on the hull was about 17 knots max, if we could make it in those seas - so that would mean another 3 hours pounding through the seas to HNL (versus about an hour on the foils.)  The boat is not designed to make a take-off run in rough water, so an open ocean take-off would be a challenge - especially in the dark.  All this very like a floatplane or flying boat.  The only way to possibly do this was to find the crest of a wave and try to skim along the crest, like a surfer.  Once foil borne, the boat could then be turned on course.  The Skipper was very skilled and we accomplished not only a successful take-off, but managed to remain foil borne for the rest of the trip to Honolulu.

It was with great relief - both to the crew - AND to the pax -  when we began our approach into HNL Harbor.  As we got closer, I could see a sea of flashing red and blue lights along the docks - as every ambulance and emergency vehicle on Oahu had apparently been dispatched to meet our arrival.  We remained in the wheelhouse until everybody had departed; I then held my nose and squished through 2-4 inches of vomit, down the stairs and off the boat onto the dock.  Home at last!  I pitied the poor crew who had to spend the night fumigating and cleaning up the boat.  We had brought everybody safely across from Kauai, and the boat had suffered no malfunctions; but it had demonstrated clearly, its operational limitations....

This one fine picture I took returning to Honolulu one day.
It was the departure of the SS Mariposa for San Francisco.
(The Mariposa ran for many years for Matson but was sold later to Pacific Far East Line.)

Being in the right position to snap this picture from the bridge of the Jetfoil was a unique opportunity.
It's truly a picture of a different Time and Place.
Within a year or two, taking a passenger liner from Hawaii to the Mainland passed into History.

Copyright 2025 Robert Bogash.  All Rights Reserved