Slo-Mo-Shun Sets the Pace in 1950

Every unlimited boat owner in Detroit had been working for nearly a year to prepare for the Gold Cup and Harmsworth races in 1950, when news of Slo-mo-shun IV's 160.323 m.p.h. world's record run reached their ears on June 26. It was not only a shock to these boat owners who had been preparing to meet Miss Canada's challenge, since she had made 138.64 m.p.h., her North American record in October 1949, but also to veterans like Art Bobrick, Chairman of the APBA Racing Commission. He had thought that Stanley Sayres, owner of Slo-mo-shun was doing some wishful thinking when he had said that he would beat Campbell's world's record of 141.74 m.p.h. Instead of going up to Seattle to observe the event he sent Kent Hitchcock in his stead, a move which, "he will regret for the rest of his life," so he says.

Horace Dodge's My Sweetie with Bill Cantrell up, was the Gold Cup winner of 1949, Stanley Dollar's Skip-a-long winner of the Harmsworth, Silver Cup and Marathon races at Detroit had been lost in Lake Tahoe, California, so it was up to Jack Shafer with his Such Crusts I and II driven by Dan Foster and Dan Arena to defend the Harmsworth when the challenge came from Ernest Wilson of Ingersoll, Canada, and owner of Miss Canada IV, right after Christmas in 1949. Shafer had tested Such Crust I early in the fall and obtained 127.063 m.p.h. on a record trial. That was not enough to beat the challenger. Everyone knew how difficult it was to break Gar Wood's long standing record of 124 m.p.h. and Campbell's 141 m.p.h was likely to stand for a long time. Dodge started to prepare four boats, one with two Allisons, Delphine X, it was called, and Walter Dossin commissioned John Hacker designer of My Sweetie to build a new Pepsi with two Allison power plants. So when the news broke of the Slo record the Detroit group had three boats which were tried, and two prospective boats, that were thought able to meet Miss Canada, since no one had counted on a new boat from the west coast to do the job. "You cannot develop a boat like that over night," some of the wise ones opined.

But Slo was not a new boat any more than the new Blue Crown Specials which Lou Moore brought to the Indianapolis Motor Speedway in 1947, and took both first and second places. They were the result of several years of experience and careful preparation. Every year following World War II, Stanley Sayres and Ted Jones had been observers at Detroit during the Gold Cup, Silver Cup and Harmsworth regattas. Sayres bought Pop Cooper's very fast 135 after Cooper's untimely death. They learned a lot of lessons from that boat, so I understand, and it greatly influenced their thinking when the latest Slo was designed. The boat was built by Anchor Jensen at the Jensen Motor Boat Co., in Seattle, the gear box designed by Donald Spencer of the Western Gear Works. Hi Johnson of Newport Beach, Cal., furnished the propeller which was finally used in the record making boat. Their first trials were made with another kind of prop so Stanley Sayres told me, but when Johnson promised at least twenty m.p.h. more speed his design was tried. As I recollect they got 26 m.p.h. more speed with the new design. This was the kind of a boat which Sayres was bringing east for the Gold. Cup and it had the best heads in the east trying to figure it out.

Pepsi could not be readied in time for the Gold Cup and Bill Cantrell trying out Dodge's Delphine X in preparation for the Gold Cup time trials flipped on the lower turn and the boat sank. With these boats out Slo only had to beat My Sweetie and the Crusts. They were the only tried boats in this area. As soon as she arrived Slo was recognized as a California type three pointer against which were a twin step hydro My Sweetie designed by John Hacker, Such Crust I a Ventnor design and Such Crust II designed by Dan Arena, both three pointers. All of these boats were designed to take heavy weather, after their sad experience in 1948. They were much heavier than Slo and all had the same power plants, V-12 Allisons. Everyone thought that Slo was a speed, not a competition boat, and that it could not turn fast, a characteristic of the previously designed three pointers as compared with the Sweetie which could turn on the proverbial dime.

As a result of the five regattas which were held on the Detroit River this year, Windsor Y. C. on July 5, Gold Cup at DYC July 22, DRRA Detroit Memorial Cup, Harmsworth and Silver Cup at DYC, a lot of lessons were learned. Perhaps no where else in the country has it been possible to watch the strenuous behind the scenes of these races.

The characteristics of the different designs, the performance of the boats in long and short races, the trials and tribulations of the contestants and the redesigning which Dodge, Dossin and particularly Jack Shafer have done to compete with Slo.

Propellers, boat balance and aerodynamics have all had their bearing on the attempts which have been made to meet and defeat Slo. Only in the second heat of the Gold Cup race when Ted Jones was trying to nurse Slo around because of loose motor brackets, was Lou Fageol able to lead the race, for nine of the ten laps, then oiling trouble killed the engine and Jones finished first to win the heat. It was the only race during the season in which Slo while running was headed by another boat. In the first heat of the Silver Cup on Labor Day, Pepsi was in the lead for a short distance after coming out of the first turn but within a mile was passed by Slo without effort. It went on to win at an average of 104.318 m.p.h. against Chuck Thompson's 96.77 in the Pepsi. In the last heat of the Silver Cup Thompson gave it everything and made the fastest average over the five nautical mile course of 107.394 m.p.h. That is a record for a boat of any type in competition. Slo had been eliminated before this heat by a seized propeller shaft bearing. What it would have been had she been running is speculation.

Propellers have been the big problem this year. Even Slo had three designs according to Hi Johnson. All the propellers were made from bronze except that on the Pepsi which was a special design steel forging carefully machined, probably on a Keller profiler and must have cost around $2,000 at present day wages. The cast bronze wheels lend themselves to quick changes and minimum costs for custom made wheels. In Detroit, Stannus wheels have been used by most of the boats. Between the Gold Cup and the Harmsworth races Crust I and II were both completely rebuilt and practically redesigned. The wheels which they had previously used were useless after the changes. Dan Foster and Dan Arena were changing wheels by the hour just as fast as they could change them and then order another combination. They now have another wheel development which they hoped to try out at Lake Mead on Nov. 11, but had some shaft trouble and did not get started in the race.

Take the Hi Johnson wheel which was designed for Slo. There are several problems which have to be considered in the design of these wheel; the angle of the prop shaft relative to the bottom of the boat and its angle when the boat is at speed. This propeller is of the so-called surface propeller type. Only the lower blade enters the water at racing speed. By properly balancing the boat it is possible to get the propeller shaft almost horizontal. That means that the blade thrust is to the rear instead of partially rearward and partly upward. Where this is possible, I understand, the slip is reduced from 40 or 45 per cent, characteristic of an immersed wheel to 25 or 35 per cent with a surface type wheel. Johnson can design a wheel to push upward or pull down when he knows the normal running position of the propeller shaft. The surface propeller is particularly adapted to the three pointer hull because it is possible to balance this so it will run with only the rear edges of the sponsons bearing on the water and supporting the boat weight and the propeller shaft and wheel hub supporting the sterna As a result only the lower half of the prop is immersed in the water. In a previous issue of MoToR BOATING I. told how one driver borrowed a Johnson wheel and tried to use it submerged like his regular prop. He could only turn his engine about 1,350 r.p.m. instead of 3,200 with a regular wheel. There is nothing new about surface propellers of course, and Harry B. Greening who used to race the Canadian Gold Cuppers named Rainbow called my attention to the wheels which he used thirty years ago, He had two 35 inch diameter by 32 inch pitch Hyde wheels with: two 300 h.p. engines and immersed the blades only 9 inches. When he went to an immersed wheel he had to cut down to 19 by 30 inch wheels.

With immersed wheels one boat had a 14 by 24 inch wheel to start and then ran most successfully with a 11.75 by 20 wheel. The latter allowed the engine to rev up and give better acceleration when coming out of a turn. At the same time the top speed of the boat was sufficient. Now there is an effort being made to vary the pitch of the wheel so that when the boat is slowed down with a surface propeller it will have a different effective pitch then when at top speed. You might call it a variable pitch prop with fixed blades, for better acceleration at low speeds and lower engine r.p.m.s at top boat speeds.

Closely connected with the propeller problem is the angle of the drive shaft, its length and support. Until Slo entered the racing picture, Miss Canada IV was the principal exponent of the direct drive from engine to propeller with a short shaft. The prevailing design was to put a gear box in front of the engine, either as a separate unit or built into the front end of the engine. With this design the propeller shaft passed beneath the engine crankcase and entered the water at a considerable angle. A very long shaft was required. When you consider that this shaft might turn 10,000 r.p.m. at top speed, the problem of supporting it properly was very critical. If there was the slightest unbalance it would whip. If the bearings get out of alignment due to the twisting of the boat they would bind and seize. The long shafts are also long torsional springs which vibrate due to changes in driving load when the prop leaves the water or the engine speed changes suddenly. Supporting the shaft at the propeller is another problem. With an immersed wheel the slip stream into the wheel must be so designed that it does not reduce the wheel efficiency. My Sweetie and Pepsi have a tunnel to house and protect the shaft. This is like a keel on a sail boat. The propeller is supported at the aft end. On the first boat this is made of welded steel, and on Pepsi from a magnesium casting, in order to reduce weight and take the torque from the twin Allisons. In the first trial runs this boat had trouble in both the thrust and pinion shaft bearings at the gear box. This is located between the two Allison power plants. After a steady bearing which prevented this shaft from whipping was put in the tunnel, midway between the gear box and the prop support bearing they had no further trouble.

With surface propellers there is no need of housing the shaft. In fact some of the drivers have greatly increased the diameter of their shafts so that they will act as a supporting surface and help lift the stern clear of the water and surface the top half of the prop. Slo used a V-shaped two-legged prop shaft support and some of the other drivers are wondering if this did not give more support to the stern than the streamlined vertical support customarily used. I noticed that Such Crust I in its latest version was planning to use a V prop strut.

Boat balance is very critical on these new three point design, which are sometimes called California type. They are virtually flying boats for they are frequently designed so that the deck and the bottom form an airplane thick wing section. Theoretically this means that the sponsons only have to support part of the weight, the aerodynamic lift taking quite a bit off the water. The boat has to have enough lateral resistance at the center of buoyancy so the rudder reaction has a fulcrum point. Fins on the inside of the sponsons at the point of support provide some of the stability and also trap air under the boat at the same point. This point is close to the center of gravity of the boat and the balance of a boat is so close, especially with the small ones like the 135 class that a difference of a gallon or two of fuel or the change of a driver will make the difference between success or failure. If a boat leaks and water gets into the stern the balance is completely upset. The bow tends to lift and if it does there is great danger.

It was this lifting that probably caused Pop Cooper's death. At speeds of over 100 mph, the force of the wind tends to lift the bow. The higher the bow lifts the more effective the wind is. A boat don't have to lift too far at high speeds to flip over on its back. These boats have to be driven with an educated toe. Gar Wood has always claimed that they should be barred from high speed unlimited boats because of this danger.

Boeing's aeronautical engineers cooperating with Stanley Sayres and Ted Jones seem to have licked this problem. They have developed a so-called spoiler on the bow of the boat. This is aero design and unfamiliar to boat men but look at any of the photos of Slo running at speed and you will note that the boat stays level in high speed running. You might explain the action in this way. When the bow raises the spoiler kills the air lift on the top surface and causes a suction on the bottom surface of the bow. This pulls the nose down. Conversely when the bow dips the suction or lift increases on the top surface and the boat is leveled off again. I cannot tell you how to design it but it seems to work beautifully.

Already J. J. Taggart of Canton, Ohio, who has the Seven Liter Tommy-Ann [sic] has been experimenting with an aileron like fin mounted above the deck at the bow. Several other three pointers are trying out variations. They have suddenly become aerodynamic conscious.

This nice balance combined with the surface propeller introduces some other problems. Slo skips along over the water for a tremendous distance after the engine is shut off. In fact it seems to lift the prop up and lower its bow when you want to slow down. During the Silver Cup race we had a remarkable demonstration of the difference between Slo and Pepsi the dual hydroplane type of boat with immersed propeller. Lou Fageol coming up from behind passed Chuck Thompson in Pepsi just before reaching the starting line. He crossed three seconds ahead of Pepsi going away. He had to shut off so far from the turn, in order to slow down, that Pepsi passed him and went into the turn ahead. The turn was 1.5 miles from start. Thompson's boat with immersed prop slows down just as soon as the throttle is pulled back. Thompson was a hundred yards ahead of Fageol, I'm told when Slo straightened out. Within a mile he was in the lead again.

When a boat handles the way Slo does and won't slow down, the question is whether flaps like those used on a dive bomber, could be used under the rules. This boat would be much faster in competition if it could be braked going into the turns. Another characteristic observed by a number of people was the tendency of the engine to rev up when the boat started to coast. I am told both connecting rods and valve stems had been stretched during the Gold Cup race. The engine was torn down and rebuilt the Harmsworth, when this was discovered.

Turning was questioned when it was said Slo was a fast three pointer. This was quickly forgotten after her first runs at Detroit. The reason was obvious when a study of the sides of the boat was made. Aft of the sponsons the vertical plywood sides are warped so that they are about 45 degrees at the transom. Heretofore it has been the practice to keep the sides vertical right up to the transom. These square rear corners dig in when turning but not so the new design on Slo. Before the Gold Cup the Crusts had a small anti trip projection on the rear corners which was new but after the Gold Cup it was noticed that Shafer had incorporated: the same wide 45 degree surface on either side of the transom.

Few designers or boat men realize the terrific forces involved in steering a high speed craft weighing two to four tons. Slo originally had two rudders but one located on the starboard side about eight inches off center seemed to handle the boat very nicely. It was operated through a Michigan Tool Co., cone type worm and gear. An arm on this gear was attached directly to the rudder arm. All the fittings were mounted on the transom. Pepsi originally had bronze rudders but in the first high speed run they were found inadequate. They were completely rebuilt and twin hammer forged steel rudders were provided. They cost about $500 a piece, I am told, and give a good idea of some of the incidental costs of operating boats of this kind.

Water pressures are little appreciated until some accident takes place. All the Harmsworth boats had their bottoms sheathed with hard aluminum sheets that were fastened on with countersunk flat head screws. The sheets were attached to the planing surfaces and under the stern. On Pepsi the plates were joined at the center, since the Vee shaped steps are not flat like the old single step hydroplanes. These plates are about 3/16 inch thick. In the first trial of Pepsi water got into the joint at the center line of the keel, worked under the aluminum and then proceeded to roll it off the boat bottom just like rolling a newspaper. It could not have been sheared off with much higher pressures but when this rolling action took place it came off the screws just like unfastening coat buttons. It was corrected by putting an overlapping longitudinal strip over the point of the V along the center line of the boat.

During the interim between the Gold Cup race and the Harmsworth, Jack Shafer and Horace Dodge completely rebuilt their boats. My Sweetie went back to the boat builder and the sides were increased in. depth to stiffen the hull. It also permitted the fuel tanks to be placed on each side of the engine so they would not change the balance of the boat as the fuel was consumed. Then Dodge tried to use a water injection model of Allison engine but was unable to make it work properly so at the last minute put in a standard Allison again.

Jack Shafer who had suffered gear box trouble with his boats used up the last reserve gear box and Dodge loaned him another type of box. To use it he had to turn the engine around and drive through the box and to the propeller shaft. When this change was made in Such Crust I the hull was also changed to ease its turning, the sponsons extended to the rear to balance the boat with the new weight distribution and a whole series of new propellers designed to match the new hull design, and try to use a surface propeller. It was a courageous step to take with no time to make proper experiments before the Harmsworth. He did the same with the Such Crust II but had better luck and made the team although the boat was not as fast as it had been in 1949, when it made nearly 100 m.p.h. But he has not stopped in his program of developing the Such Crusts. The latest move is to replace the Allison power plants with the Packard Rolls Royce engines. These have been rebuilt for this service by Horace Dodge. The gear box like that on the Slo is on the rear of the engine and drives the propeller through a short shaft. It is interesting to observe that the gear teeth in both the Slo and the R-R boxes are straight tooth. In operation they seem to be much smoother than the gears of the bevel type used in all of the previous gear boxes. The question uppermost in the minds of all who have seen the new installation is how the boat will turn. The R-R turns in the opposite direction from the Allisons and therefore the driver will have to fight prop torque in making turns.

At this writing the Such Crusts and Slo-mo-shun IV were to have raced at Lake Mead but shaft trouble kept them out of competition and My Sweetie with Bill Cantrell and Horace C. Dodge dividing the honors of piloting it to victory in all heats. By the time you read this all of these boats may have made a record in the Salton Sea trials which are scheduled for the last of November.

Not since the days of Gar Wood has there been as much development going on in all classes and more competition for top honors in the Unlimited Class. 1951 should be a big year in Boat racing. It looks like three pointers with aerodynamic control will make records in all Classes.

(Reprinted from Motor Boating, January 1951)


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