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10/03/05- Some very good news: Tim Arfons has completed reassembling the complete T58 engine with output reduction gearbox and SCS crashbox. In two weeks time, I will be heading up to Akron Ohio to pick up the completed engine and also to pick up the Sage #8 outdrive for the boat. The plan is to get the engine and rig it up in a test stand so that we can test run the engine and familiarize ourselves with its operation.

In the meantime, we have connected with a Long Island hull builder who we will name in the near future. This company will custom build a hull for this project and will also take part in the rigging up of the engine and the outdrive. I have also been continuing to acquire the necessary components to do the plumbing and electrical work for the project. Please follow this link to page 2 of this project.

6/27/05- Mark Nye has finally completed his modification of the power turbine housing and has now boxed up the parts to be sent back to Tim Arfons in Akron, Ohio for final assembly.

After cutting and trimming the power turbine housing, and making sure that the output assembly fit, the next step then was to remove the drive assembly to reweld the now re-shaped power turbine/exhaust housing. According to Mark, the Hastelloy X material of which the power turbine housing is made is very difficult to weld. Subsequent testing, however, showed the welds to be free of cracks even after two 800 degree thermal cycles.

After finishing off the casing, Mark reassembled the output assembly to the power turbine housing to verify fitment, and his difficult job was completed. The pictures below show a bit of the chronology and reveal how these modifications have provided a very neat and compact output reduction assembly. (next entry)


Above: After cutting the casing to recontour it, and making sure everything fit, it was time to reweld it in its new configuration. On the left, the Hastelloy X casing is shown partially welded. After welding, the casing is ground to remove excess weld bead.


After getting tired of welding, Mark decided that a couple of well placed pieces of duct tape would do the trick. Just kidding, of course. The middle picture shows what the welds look like from the inside of the scroll assembly. Note the carefully positioned bottle of Molson's Canadian peeking out through the exhaust housing in the picture on the right. Beer: lubrication for the soul.


The picture on the left shows the finished casing undergoing red dye inspection for cracks. Everything tested out perfectly. As they say, "Say NO to Crack." Even with the recontoured casing, Mark had to fabricate special tools to get to the bolts. The picture on the right shows Mark putting his elongated tool to good use. (Sorry for the choice of words there.)


These pictures show the output assembly being fitted to the power turbine casing to test the fit. Mike Sage of SCS Gearbox cleverly fabricated the brake rotors with large holes in them to be able to get to the bolts that mount the carrier bearing onto the output reduction gearbox. The picture on the right shows the finished output shaft brake assembly and the alternator and power steering pump drive pulley.


These pictures are closeups of the unit completely assembled with the reshaped casing. Note that it is still quite a tight fit, a result of the assembly's compact nature.


The picture on the left shows the input side of the output reduction gearbox. The plugged hole on the left is the input shaft for the output reduction gearbox, which will receive a 20,000 rpm input directly from the free power turbine. The middle picture shows the business end of the assembly. The engine exhaust is admitted through the large opening on the left while the large companion flange on the right side of the picture will couple directly to the boat's outdrive, turning it at a maximum speed of 6,000 rpm in forward or reverse.


The two pictures on the left are great shots of the completed power output assembly. This unit will attach to the rear end of the T58 gas producer unit back at Arfons's shop. You can see the the finished assembly is quite compact and that the output companion flange does not stick out much past the exhaust outlet, especially once I connect a large exhaust stack. The picture on the right shows the parts being crated up to be sent back to Ohio for final assembly.


5/27/05- After a number of discussions between Mark Nye and myself, Mark came up with the idea to cut and modify the power turbine housing between the two "cheeks" of the power turbine housing, to make room for the output reduction gearbox and crashbox assembly. More specifically, Mark will cut and recontour the power turbine housing so that the bolts that hold the output reduction gearbox onto the power turbine assembly will be accessible. The problem stemmed from the fact that, in order to minimize the overall length of the power unit and transmission, I decided to have the turbine shaft brake rotor and alternator drive pulley mounted on the front output of the reduction gearbox. While this allowed the crashbox to be close coupled to the output reduction gearbox, significantly shortening the length of the assembly, this also created a very crowded situation at the connection between the output reduction gearbox and the power turbine housing, making the bolts completely inaccessible. Mark's fix is a great solution to the problem, as you can see in the pictures below.

Pictures courtesy of Mark Nye

As you can see in the pictures, Mark started by cutting notches in the power turbine casing in the valley where the power turbine shaft comes out at 20,000 rpm. Cutting these notches has allowed him to recontour the shape of the valley, providing enough room to mount the output reduction gearbox assembly with its enlarged brake rotor and drive pulley, while still allowing enough room to get a small gear wrench in there to tighten up the bolts. All that remains now is for Mark to reweld the notches in the casing to make one solid unit once again, and then to reassemble the output reduction gearbox/crashbox to the power turbine assembly. Once that is complete, he will send the unit back to Tim Arfons in Ohio, who will reassemble the power turbine/output drive section to the gas producer of my T58.

Much kudos to Mark for his work on this project. The job he performed was not an easy one; nevertheless it seems as if he has performed it flawlessly. You can see how difficult it is to get to the bolts, even if that big brake rotor was not in the way. Without his little "surgery", we would have never been able to get the gearbox onto the back of the power turbine. At this point, my power turbine housing has had more reconstructive work than Michael Jackson.

I truly believe that taking the extra time to get the power takeoff assembly together in a neat and clean fashion will be well worth it in the long haul. By minimizing the length of the engine and drivetrain, I will have more cockpit room, and will hopefully be able to squeeze at least 5 passengers aboard. I also expect great reliability from this setup. (next entry)

12/21/04- Some news on the progress of the T58 engine and drive train for the boat project...

We've been having a difficult time assembling the completed output reduction gearbox to the rear of power turbine assembly. Basically, the front mounted brake rotor on the output reduction gearbox is totally blocking access to the bolts required to mate the power turbine and the reduction housing. We got Mark Nye involved, and his suggestion was to cut a window into the power turbine housing/exhaust volute to allow access to the bolts from the inside of the exhaust housing. So, we crated up the power turbine housing, and sent it up to Canada where Mark Nye will perform the work. This power turbine assembly travels more than I do; soon I will have to get a passport for it. Updates to follow... (next entry)

Boxed up PT Assembly


11/28/04- Tim Arfons and Mike Sage are working together to iron out a few minor details in getting the output reduction gearbox and crashbox assembly mounted to my power turbine housing. There were a few minor conflicts which are delaying the completion of the assembly, but once they are cleared up, Tim will be able to mount the completed output section to the gas producer. I hope to be able to drive out to Akron some time before Christmas to pick up the engine. I can't wait to test run it in my backyard!

While I've been waiting for the engine work to be completed, I've been trying to keep myself busy. I made a full scale 3D mockup of the engine so I can bring it to the hull builder and give him a sense of the engine's size so he can build the hull to suit it. I also took a trip to the local West Marine store to pick up some of the switches and components I will need to wire up the boat's electrical system. It's still a little early for that, but I can always use some of the switches when I make up a panel for my T58 test rig, since I plan on test running the engine to familiarize myself with its operation, before I mount it in the boat. (next entry)


10/09/04- The procurement of parts continues as I received a package from Nye Thermodynamics in Ontario, Canada. Mark Nye produces a line of parts for the T58 engine to be used in a marine application that he developed after building his own awesome T58 powered boat. Mark is a skilled craftsman and the quality of his parts reflects this.

The picture on the top left shows the Nye Soft Start Solenoid, which controls the in-rush current to the starter motor to lessen the shock on the starter shaft when the engine is spooled up. The picture on the top right is the afterburner control module and associated timing relay. The afterburner control features separate controls for afterburner fuel flow and timed control of streak fuel, which ignites the afterburner. On the bottom left are assorted plumbing fittings to make it all work right, including a fuel de-aerator which will be very useful in choppy water. Mark was nice enough to send me a full scale drawing of the T58 so I can make a plywood mockup for the hull builder. Speaking of hulls, I have been talking to a couple of local boat builders who seem to be interested in the idea of building a custom hull for this project, and mounting the engine and outdrive as well.

Meanwhile, Tim Arfons has the output reduction gearbox and crashbox back at his shop, and he will be working on reassembling everything which means that we'll be going on a road trip in the next few weeks or so to pick up the engine and the outdrive. I have decided to go with Mike Sage's SCS #8 Surface Drive for this project. (next entry)

9/25/04- Mike at SCS Gearbox has completed mounting the SCS Zero Drag Crashbox and the output shaft drive brake and alternator pulley to the Rolls Royce Output Reduction Gearbox for the T58. SCS Gearbox furnished all of the machined metal required for this job. The drive will come off the free power turbine at 20,000 rpm, and the speed decreaser will reduce it to 6,000 rpm. The crashbox does not provide gear reduction but will allow a Forward-Neutral-Reverse capability.

The picture on the left shows the aluminum mounting plate mounted to the rear of the output reduction gearbox and the crashbox mounted to the rear of the plate. The plate will later be cut down to final dimensions before the completed power unit is installed into the hull. The plate will be used to mount the the unit to the stringers of the boat. The middle picture shows the front side of the assembly. On the front is the output shaft brake assembly as well as the alternator drive pulley, and also the power steering pump drive pulley (still to be added). The picture on the right shows another perspective; note the Wilwood high performance brake caliper, which will stop the output shaft from turning so that the crashbox can be shifted in and out of gear. Also note the beefy mounting brackets on the reduction gearbox. These will be the primary means of mounting the engine to the hull.

The completed output drive unit will be on its way back to Tim Arfons in the next few days. Tim will then reassemble my T58 engine and mount the drive assembly to the rear of the engine. In the next few weeks, I should be able to go and pick up the finished power unit. (next entry)

8/15/04- With the engine work completed, Mike Sage is working full force on developing a custom input for his SCS Zero Drag crashbox, and mating his transmission onto the rear of my T58. Mike is going to first provide a 3/4" aluminum mounting plate that will bolt onto the rear of the Rolls speed decreaser gearbox. He will then close couple the crashbox directly to that aluminum plate. The crashbox will have an elongated splined custom input shaft that will run all the way forward through the speed decreaser to the front side of the gearbox. Mike and I decided that, in the interest of cutting down the length of the engine and transmission package, that the output drive brake and alternator pulley be mounted on the front side of the speed decreaser gearbox. This will allow the crashbox to bolt directly up to the speed decreaser. Mike will machine up a 9.75" steel brake rotor with a splined hub to sit on the elongated crashbox input shaft, and a vee belt pulley on the front side of the rotor which will be used to drive an alternator. The elongated shaft will be supported in a bearing mounted on the front part of the speed decreaser. An aluminum subframe will be made to support the rear end of the crashbox. The subframe will be mounted off of the aluminum plate, and will later bolt down onto the stringers of the boat once the whole engine and transmission unit is mounted into the hull.

I will be considering using Mike's stern drive, called the Sage # 8 Drive. Knowing Mike's reputation for rock solid parts, the Sage Drive seems like a really attractive unit. It is essentially a combination of a Mercury Speedmaster drive and an Arneson Surface Drive, seemingly capturing the positive traits of both units. The drive allows the propeller to be trimmed for angle, as well as X-dimension without affecting the angle of the prop. To learn more about this drive, click here. (next entry)

6/28/04- Having an initial consultation with Mike Sage of SCS gearbox, Tim Arfons modified the Rolls Royce Gnome output reduction gearbox for the turbine boat application. Normally, power is taken off of the front of the speed decreaser box to drive the helicopter transmission. However, in this application, the SCS crashbox will be driven off the rear of the gearbox, and must be modified as such. The front output will be retained as well, in the event that it is needed to drive an alternator pulley (I intend to run the alternator off the engine output shaft) or perhaps the shaft brake. SCS gearbox will be working on custom designing the input side of the crashbox in the next weeks. In the meantime, I have completed all of the wiring schematics and switch assignments for the boat, and am eagerly awaiting the completion of the engine overhaul and modifications. (next entry)

5/18/04- I have posted a video of the engine's second test run, performed by Tim Arfons in his shop in Akron, OH. Please follow this link to watch the video. In the video a "dummy" power turbine case is attached to the engine, but the power turbine and all associated parts have been removed, so the engine is essentially a turbojet at this point.

The operation of designing a custom input for the close coupling of the engine's output reduction gearbox to the marine transmission is currently taking place. While the engine gas producer is in Arfons' shop in Akron, the output reduction gearbox and another stripped dummy power turbine case are on their way over to SCS Gearbox in Bellevue. Stay tuned for more updates on that.

SCS Zero Drag Crashbox

While this is going on, we are continuing to look at the overall design of the boat. We are going to focus on keeping the noise levels under control, especially since it is a larger boat and I will be entertaining numerous people at a time, possibly for long periods. We are examining ways to insulate the engine bay from noise, while treating the intake and exhaust somehow to reduce the volume of the noise. We will be getting more into this as the project moves along. (next entry)

4/15/04- It's alive!!! This week Tim Arfons successfully started and ran the gas producer section of my T58 engine. Arfons ran the engine for about ten minutes, modulating power from a 55% idle speed up to around 90%. At 90%, the gas producer was producing enough thrust to slide the engine stand across the floor, and it required two guys to keep it from running away. In the next few days I will post a video of the start and running of the engine. Stay tuned! (next entry)


3/30/04- The T58 gas producer is still in the work stand being overhauled. Apparently it is difficult to find a T58 fuel controller that doesn't leak, although I am confident that Tim Arfons will get the job done. Some good news, though; the power turbine modifications have been completed by Columbia Helicopter and the power turbine has been reassembled and stored for the time being. The next step on the output end of the engine is to prepare the Gnome output reduction gearbox and send it to SCS gearbox, who can then get on the job of custom fitting the crashbox transmission to the engine as per my specifications.

I have just about completed the design of the boat, and I am just waiting to get the engine done before I move to the next phase of having a custom hull built to my design and specifications. I think I may have located a local boat builder who can fabricate a fiberglass hull for me. More on that later... (next entry)

2/05/04- Some news on the T58 engine; Just prior to the first run up of the gas producer on the test stand, it was found that the fuel control is faulty, and the manual cutoff stopcock in the fuel controller is stuck in the open position. The engine also has a number of leaks in the fuel lines. These problems are indicative of an engine that had been sitting for a long time without being used or properly preserved. We are attempting a fix, but if necessary, the fuel controller might have to be replaced. Everything else so far appears to be in good shape. (next entry)

12/10/03- Engine work continues. Tim Arfons has separated the power turbine module from the engine and stripped it down to the bare casing, and he has sent it to Columbia Helicopter who will begin the process of modifying the casing so that the exhaust outlet points upward. In the meantime, Arfons has mounted up the engine gas producer on the work stand and has begun to clean it up first by stripping the old wiring, and then by fixing or replacing any bad or missing parts. He will eventually run up the engine on the test stand as a gas producer, where he can set his topping and bottoming governors on the fuel controller. He hopes to get that test run on video so I can put it on the website.

I am getting a clearer picture of how I am going to rig up the drivetrain. The power turbine is going to be fitted with a Rolls-Royce Gnome output reduction gearbox, which has slightly better low rpm lubrication characteristics than the General Electric SDG, and is a little more rugged. The Rolls-Royce Gnome is a license built GE T58. Coming out of that will be an output shaft brake, which will feed an SCS Gearbox Zero Drag F-N-R crashbox. The crashbox is designed so that when forward is engaged there are no moving parts inside the transmission, which reduces internal drag and adds a few miles per hour to the top end. Mike Sage at SCS has a reputation for building rock solid gearboxes for marine use and other uses as well, and should easily stand up to the monstrous torque of this turbine. We are going to try to close couple the crashbox to the output reduction gearbox. Tim Arfons and SCS gearbox will work closely on accomplishing this. Once the gearbox is coupled to the engine, it is simply a matter of dropping it in a hull and connecting it to an outdrive, which will most likely be an Arneson Surface Drive at this point. We definitely intend to design this boat around its engine and drivetrain. (next entry)

10/28/03- With the engine work commencing, I have some time to think about the design of the boat, at least in general terms. I will be using lessons learned on the last turbine boat project when building this boat.

I have a few basic requirements for this boat. The boat must be able to go above 100 mph safely. With 1,370 horsepower, this shouldn't be too much of a problem, but a hull with too much length or beam will make the boat slower and heavier. At the same time, the boat must handle the rough water where I do most of my boating while remaining stable at high speed, so the boat cannot be too small; a balance must be struck. I also want to make sure that I have enough fuel to run for more than two hours, so I will need in the neighborhood of 250 to 300 gallons of fuel capacity to keep the thirsty turbine running. The boat will have to seat at least four, and preferably five, and I would like to reduce the noise of the turbine down to levels that are more comfortable for the passengers. I am not only looking for outright performance but also a degree of practicality.

I will be going with a narrow beam, deep vee monohull with a stepped hull design for this boat project. Ultimately, a catamaran would yield higher speeds and faster acceleration, however I am going to opt for the everyday usability of a deep vee which will also give me added safety. I am looking for a high performance vee hull between 28 and 30 feet in length to acheive these goals. At this point I am not looking aggressively for a hull. Until the engine is completed, the project will move along at a relaxed pace.

For now I am going to be focused on getting the engine 100% completed and ready to run in a boat. I am also beginning to procure some of the major components, particularly in terms of the driveline.

An output reduction gearbox will be installed at the rear of the engine. The SDG reduces output speed down to a usable 6,000 rpm, and also offsets the drive axis down which will help me to line up the engine to the subsequent driveline components. The SDG will be fitted with an output shaft brake kit which will allow me to stop N2 from rotating so that I can shift the transmission, which will be a crashbox type transmission. A crashbox is a very basic and lightweight racing transmission which normally can't be shifted while it has input speed anyway, so it seems perfectly suited to a turbine application. The crashbox will provide forward-neutral-reverse capability. The crashbox will then feed into the outdrive. I intend to use a surface piercing drive for this application, as it seems the most efficient way to put the power to the water for the best high speed performance. I am considering a number of different surface drives, as there are quite a few available on the market, including the Arneson Surface Drive, SARO Drive, Stinger Drive, Pulse Drive, and Weismann Surface Drive.

This page will be updated as engine work progresses and as we continue to procure materials for the project. (next entry)

10/13/03- Well, here we are, we're at the beginning of our most ambitious project to date. This is going to be a long term project, and we are in no big hurry to get it done. The project is going to be focused around our General Electric T58-GE-8F engine. As you know from our Turbine Engines page, this engine produces a takeoff power rating of 1,370 shaft horsepower at an N2 speed of 20,000 rpm, and is incredibly light and rather compact for its power. This, combined with a tremendously fat torque curve makes it the perfect candidate for a high performance boat engine.

The engine was acquired on Ebay. The engine is complete and is in decent condition, except it does not have a starter, and upon initial inspection, it was found that the fuel pump drive shaft had sheared and the fuel pump itself was frozen stuck. The fuel pump can be replaced fairly easily. I consulted Tim Arfons on the engine, since he is a real expert on T58's, and decided the engine repairs were better off in his hands.

The first step is to separate the power turbine section from the gas producer, strip the turbine wheel from the power turbine casing, and then perform the delicate operation of modifying the casing to work in the exhaust up position. On the stock engine, the exhaust outlet faces to the side.

In the meantime, I am beginning to design the layout of the boat. Stay tuned for more on that... (next entry)

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