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Feb 15, 2012, 10:00 PM
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MARAD/Grumman HS Denison

Two years ago I fell in love with this wonderful ship.
Data research was really hard but I stubbornly looked under every stone and now I believe to have enought infos to start building.

From "Ships that fly",JOHN R. MEYER Jr

Overlapping the events just described in connection with SEA LEGS was a
series of developments within the Maritime Administration (MARAD) that
started in 1955. These were sparked by the commercial application of
hydrofoils in Europe and the researchb eing sponsoredb y the U.S. Navy. The
Maritime Administration Coordinator of Research, Charles R. Denison, was
enthusiastic about the future commercial potential of the hydrofoil and in
1958 sponsored an extensive parametric study carried out by Grumman
Aerospace Corporation and its affiliate Dynamic Developments, Inc. The
purpose of the study was to determine the type of hydrofoil craft best suited
to future express-cargo and passenger applications and establish design
criteria for such craft. Speedso f 50 to 200 knots, displacementsfr om 100 to
3,000 tons, and ranges from 400 to 3,600 nautical miles were considered. Foil
section shapesa nd arrangementsp, ower plants and propulsors,h ull form, and
control systems were treated including several preliminary designs for
oceangoing ships. Based on the favorable results of this study, MARAD
contracted with Grumman in 1959 for design studies for two test craft. One
was to have a conventional powerplant and the other a provision for a
lightweight aircraft nuclear power source when such a system became
available. Now that's really planning ahead!
Subsequentlyi,n January of 1960 MARAD placed a contract with Dynamic
Developments,I nc. to build an experimentalh ydrofoil capable of speedsu p to
60 knots with gas turbine engines. Provision was made for a second phase
where the subcavitatingf oils would be replaced with supercavitatingf oils.
The intent was to achieve speeds up to 100 knots with the same power plant.
Unfortunately, Charles Denison, whose vision and enthusiasm was in great
part responsible for the program, suffered an untimely death before the ship
got beyond the early design stage. It was in his memory that the ship was
later christened HS DENISON.
Although MARAD had contracted with Dynamic Developments, Inc. to build
DENISON, Gumman Aircraft Engineering Corporation, because of expanding
interest in hydrofoils, purchased interest in and eventually acquired all of
Dynamic DevelopmentsI,n c.
DENISON was launched by Grumman on 5 June 1962 at Oyster Buy, Long
Island, and began sea trials only four days later. The picture below shows the
ship hullborne with its unique foil system retracted. The 95-ton DENISON had
surface piercing foils forward carrying 85Vo of its weight, and a single fully
submerged tail foil aft carrying the remaining l1Vo. The ship's length overall
was 104.6 feet, maximum hull beam was 23 feet, and maximum draft
hullborne with its foils extended was 15.4 feet.
It is significant that the main propulsion for foilborne operations was
provided by a General Electric gas turbine engine rated at 14,000 horsepower.
It was a marine version of GE's J-79 aircraft jet engine. MARAD had obtained
two I-79 engines from the Navy and then bailed them back to GE who then
provided the marine version by the addition of a so-called free power turbine
to take energy out of the jet. This arrangement was interesting in that it was
accomplished for the total sum of one dollar. This proved to be a wise longterm
investment on the part of the General Electric Company because it was
the basis for their later so-called LM series of marinized gas turbine engines
which are extensively used in Navy ships today.
The above financial arrangement was not entirely unique on the DENISON
program because although MARAD contributed $1,500,000 for design and
construction, Grumman and 73 other companies invested from $5M to $7M of
their own funds. Now that's cooperation!
The design of a propulsion system capable of putting 14,000 hp into the
water through a single high speed propeller was a considerable challenge at
the time. Power was transmitted from the gas turbine engine through a rightangle
bevel-gear drive to a supercavitating propeller mounted at the bottom
of the aft strut. The spiral bevel gears, 20 and 2l inches in diameter and
turning at 4,000 rpffi, were designed and built by General Electric Company
and represented the most stringent requirement of any which previously had
been manufactured.T
A series of trials were carried out at speeds of 50 to 60 knots as the ship
demonstrated its ability to be stable and highly maneuverable. DENISON was
also a good performer in rough water under high winds and low
temperatures. The temperatures on some tests were below freezing, but no
icing problems were encountered during either hullborne or foilborne
operations. In comparison, it was reported that a 3O-foot escort boat was
unable to proceed out of sheltered waters during that time due to heavy icing
on its deck and superstructure. Again we have a case of who was escortino
whom ?
Following these trials, the U.S. Navy and MARAD had planned to proceed with
the next high-speed phase of the DENISON program incorporating a
supercavitating foil system.
All seemed to be on track when the Navy
decided to change course and proceed with the design of their own high
speed foil research craft, designated FRESH-I (described in the next Chapter).
Since the Navy withdrew their financial support, MARAD decided to
terminate the program and not pursue development of commercial hydrofoils
any further.
It has been said that the MARAD program, and more particularly the HS
DENISON, contributed in large measure to the growing technology base for the
design of hydrofoils. Many of the DENISON's subsystems were at the leading
edge of the state-of-the-art, and knowledge gained was invaluable in further
developments by the U.S. Navy. It is unfortunate that it did not also fulfill
the bright future originally forecast for the employment of commercial
hydrofoils in U. S. service.T
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Feb 16, 2012, 02:09 PM
Sea Dragon-Lover
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I look forward to seeing your build up.

Feb 22, 2012, 08:45 PM
Be afraid!
Cuddles's Avatar
Everyone interested in hydrofoils will find sooner than later the International Hydrofoil Socety.
This organization provided a starting point for my research as I found several infos about HS Denison and later become paramount as I contacted one of the engineers who worked at this wonder: Charles Pieroth.

Here's our correspondence.

Hello Charlie,
> > I want to make a model of the HS Denison and I was wondering if you
> > would like to help me.
> > I've read about your involvement in this project at:
> >
> > I'm looking for a photo from above of that wonderful ship so that i can
> > figure out the correct shape of the deck.
> > I've looked hard on web for this project but i've found very little
> > documentation, 90% of this coming from the International Hydrofoil Socety.
> >
> > thank you in advance,
> >
> > Francesco Fornaroli
> >

> Your request turn out to be interesting search, but I have not been
> successful in getting an answer for you. The Denison was designed by a
> company called Dynamic Developments in the 1959-1960 time frame for the
> U.S. Maritime Administration, an agency of the U.S. Department of Commerce.
> After the Construction Contract was awarded, Dynamic Developments was
> purchased by Grumman Aerospace, and the latter built the Denison at
> their (landlocked) aircraft facilities in Bethpage, New York. When the
> ship was about 90% complete it was trucked during early morning hours to
> a small shipyard on Long Island Sound in Oyster Bay; about ten miles
> north of Bethpage, where the struts and foils were fitted, and builder's
> trials took place.
> I was employed by Dynamic Developments while an undergraduate doing the
> summers of 1959 and 1960. During the latter employment I helped design
> and start construction with two others, a 18% scale version of what was
> then called the "MARAD" hydrofoil. The purpose of this smaller design
> was to demonstrate foilborne dynamic stability of the larger "Denison".
> Since the construction contract for the Denison had not been yet
> awarded, those of us designing and building the smaller version called
> it "Great Expectations". The name subsequently became the official name
> of the smaller boat.
> I later became employed by Grumman starting early in 1963 after
> finishing the major portion of my course work for a Master's degree in
> Naval Architecture, leaving in 1995.
> In response to your query I searched through my collection of hydrofoil
> photographs and found none to answer your need. I found many from
> overhead of other navy hydrofoils and test craft. I suspect the navy
> had far better availability of helicopters for taking aerial
> photographs. I also found that many drawing copies in my procession from
> the time of the design (circa 1960) have faded beyond use.
> The best I can offer are the following suggestions for locating at least
> dimensions and design dimensional information (including offsets) on the
> Denison, which may be fruitful.
> 1. A hull model of the Denison was tested at the Davidson Laboratory at
> Stevens Institute in Hoboken, N.J. The Davidson Wood Shop most likely
> built the model which was standard practice for Grumman in that time
> frame. To do so, they would have received a hull lines drawing from
> Grumman. The Davidson Archives may contain the info you are seeking.
> 2. There may be archives at the Maritime Administration that contain
> records on the Denison and/or the Great Expectation.
> 3. After Grumman ceased their hydrofoil operations I personally arranged
> for the shipment of the bulk of our engineering files to the then
> Hydrofoil Data Bank @ the navy's David Taylor facilities in Carderock,
> Maryland. We also shipped our inventory of parts and hardware to them. I
> understand the data bank is no longer in existence, but it may be worth
> an inquiry.
> 4. You might contact the International Hydrofoil Society once again, and
> ask them to put out a call to their members for information.
> Incidentally, the Denison hull shape was a direct decedent of Grumman's
> history in engineering and building seaplanes, and was in fact designed
> by the same sections of the engineering department that designed the
> seaplane bottoms and floats.
> 5. Lastly, Grumman maintained a History Center that was staffed by
> volunteer retirees. It was customary to send excess/duplicate
> photographs and display models to the History Center. I also recall
> there were a number of product models on display in the lobbies of
> buildings. I don't know what became of these after Grumman was acquired
> by Northrop. However it might be worthwhile to contact the Northrop
> Grumman Public Relations folks at their headquarters in Los Angeles.
> Hope this has been of some help.
> Good luck,
> Charlie

thanks alot for your efforts, they are very much appreciated!
I've finally managed to find a view from above of our ship...she is depicted on a glass i've found on Ebay!
It seems to be fairly correct, would you mind to give it a check?
I'm going to attach all the photos in my possession, hoping that you have something to add, before starting to draw a plan.

Thank you very much,


Your second e-mail with the attached photos and art brought back
memories; the one of the Bounty and Denison taken in Oyster Bay in fact
brought back two. I had forgotten that the Bounty was constructed for
the movie in Lunenburg, Nova Scotia, Canada. I had know this at the time.
Much latter in my career I became good friends with a gentleman who
owned and operated a fiberglass boat factory in Lunenburg. I visited the
facility several times and learned during these visits that Lunenburg
was the home port for the Norwegian Navy in exile during World War II,
and that my friend's facilities was used for supply and refit for their
I don't think much has been recorded about the Norwegian navy and their
allied actions in the war. It is a little known, but interesting role
they played in the allied total effort. The exile navy provided part of
the escorts from Halifax to Iceland for the supply convoys to Europe
from North America. They sailed in Canadian
built corvettes. The Bedford Basin @ Halifax was the gathering and
assembly point for the incoming convoys. The U.S. Navy provided the
escorts for oilers, freighters, and transports coming up the coast from
ports in the U.S. to Halifax. The Bedford Basin is geographically a
large natural harbor and the incoming convoys were resorted there for
both their destination ports in Europe and by intended voyage speeds.
( Individual convoy speed was determined by the fastest speed of the
slowest ship.) Another Canadian friend told me that at times the Bedford
Basin had over a thousand ships at anchor. The newly formed eastbound
convoys were then escorted from Halifax to Iceland by the escort ships
of the Canadian Navy together with escorts from European navies in
exile. From Iceland the eastbound convoys pick up British Navy escorts
to their destinations. The escorts from Halifax to Iceland then assumed
the escort role for convoys returning from Europe which had arrived
under escort of the British.
So much for a moment of history.

I think you will be glad to know that quite by chance I located a
drawing for the hull for the Great Expectation, which I mentioned in my
earlier e-mail. I lifted the critical offset points and expanded them
back to full scale Denison size on the attached. As I mentioned earlier
the hull form/shape was greatly influenced by prior experience with sea
plane hull/fuselage designs and wing floats. In seaplanes these
surfaces where needed to augment lift from the wings to assist takeoff
of the plane. In hydrofoils the foils were more effective in generating
lift and the hull contribution wasn't really needed.
At any rate the attached will allow you to generate the keel profile,
chines and deck edges. These three (five)lines will allow you to define
the hull shape as originally defined by Dynamic Development for the
Marad proposal. After Dynamic Developments was acquired by Grumman and
engineering responsibility transferred for the Denison was transferred
to them, seaplane experience was incorporated into the Denison hullform.
This is basically reflected in the shape of the hull forward of the main
struts between the keel and the chine. This area has been made slightly
concave, and is shaped like many/most Grumman amphibian/seaplane. One
of your photographs shows the bow-on view of the Denison hull borne,
with a near prefect bow wave rising up and peeling off. This is the
intended pattern for a seaplane about to lift off.
As noted in the footnotes on the attached the shape can be achieved by
imagining a section of a near horizontal cone with the base aft and the
apex forward beyond the bow.
I hope this information is useful.

I'm curious about your want or need for a model of the Denison and the
numerical scale.


I've enjoyed your moment of history about Norwegian navy so much, infact I consider myself as a missed historian of aero-naval ops of WWII.
I was sure to spur some memories with those photos and I'm glad it worked!
Your data is very useful and I'm looking forward to incorporate them in my drawings wich will allow me to develop a full set of plans.
Interestingly the choice of building this ship came out quite by chance - in fact while searching data about hydrofoils, I've stumbled upon the book "Ships that fly" where the Denison's story is told.
As a matter of facts, after some 20 years of airplane modeling, i fell in love of two projects told in that book i.e. Plaiview and Denison and I want to model them.
I will keep you up to date,

Best regards,


Dear Charlie,

Finally I'm starting to draw a plan for HS Denison after a hellish month.
My PC crashed again, I've lost a submarine and some other amenities...

About your last contribution, well...frankly speaking Charles, my math is awful and I've tried but failed.
I feel really ashamed, knowing that you probably spent some time working for me.
Must look harder for a naval engineer here in Milan.
I will submit to you my plan as soon as done, hoping that you will correct it.
By the way, the arrangement of forward foils is not very clear to me, specially the planform of the bottom foil.
The outer strut is a plain rectangle in planform but the inner strut seems to have some forward sweep and is clearly tapered.
Also, is not clear if the two forward foils are jointed when submerged or, as I believe, are independent and separated.
May I trouble you for a small planform sketch?
I consider you the godfather of this model and I really appreciate your effort.

Thanks again,



To testing the basic design I'm building a smaller Denison:
the little Great expectation.
A coreless 7mm motor will provide propulsion along with a surplus parkzone block.

Update: foilborne video!
Great Expectation foilborne trials (0 min 9 sec)
Last edited by Cuddles; Feb 23, 2012 at 08:01 AM.
Feb 24, 2012, 12:16 PM
Be afraid!
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I'm just back from Vasca Malaspina, my favourite basin, just outside Milan, near Linate airport.
The first flight of "Great Expectations" was quite successful; after some tweaks to the CG and stern wing incidence she flew wonderfully and sustained flight even in turns though with cavitation issues.
This should be partially cured with a piece I forgot to mount: the cavitation plate
Last edited by Cuddles; Feb 25, 2012 at 02:43 PM.
Feb 25, 2012, 02:37 PM
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Today "Great Expectations" was much admired at Novegro Model Fair, all thanks to the neglected cavitation plate!
As expected, wind was an issue: to turn tighter I had to "land"

Here's a video.

Great Expectation at Novegro Model Expo (1 min 53 sec)
Last edited by Cuddles; Feb 25, 2012 at 02:43 PM.

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