Graupner Portofino Electric deep vee

[greenman407]

This started out as a Scale Cruiser. Its speed was very modest as the twin speed 500s were wired in series to a 7.2 volt Nicd giving 3.6 volts per motor. When I rewired to 7.2 volts to both motors it picked up quite a bit. Then I purchased new prop shafts that allowed me to install Octura x-447 left and right props , now we were moving. Playing around with gearing allowed further improvements. Then came the upgrade to ball bearing performance brushed motors with adjustable timing. At present I run a Dimension Engineering's Sabertooth 2x25 rc speed control. This allows me to put 14.4 volts to the motors at full power. Water cooling helps keep the temperatures managable.

[greenman407]

Here are some pictures taken about 18 years ago that I recently had put on a disk.

[greenman407]

Here she is coming at you at speed, Its a little fuzzy but back then I didnt have a digital camera that you can preview your shots.

[greenman407]

Here is the Sabertooth 2x25. It allows me to control both motors independantly.

[greenman407]

I came upon the idea to use this boat as a submarine and boat retrieval system. Yes this boat is fast but it is also very slow and controllable and much more important.........maneuverable. With its twin screws that are counter rotating and steerable(no rudder , the outdrives pivot) and independently controllable it was perfect. If you have ever seen someone trying to push one boat with another boat its usually a lot of laughs. The pointed end of a bow touching the broadside of another is not a good platform to push against and you will get all screwed up in a hurry. Enter this.

A pushing platform that I made out of ABS and equipped with cushions so as to not mar the finish of whatever you are pushing. It bolts on and off and extends below the water line of whatever you are pushing.

I have saved several boats to date. I will have to get together a video of it in action.

[greenman407]

The downside to this speed control is that it produces a fair amount of R.F. Unfortunately in the confines of a boat you cant always put all the componants right where you would want them. So taking some advice from David Harrison at Model Solutions in Canada I made an alluminum box to cover the speed control and another one for the RX. Then I grounded everything and discharged that ground into the water by soldering onto a water pickup tube. I also used a loaded antenna. In addition to this I purchased from them and installed their transient voltage suppressors. A great improvment in radio range was noted. Before, you would get 60 feet away and the boat would lose you. I am still, occasionally tinkering with it to get more range.

[greenman407]

Here are the steerable outdrives. If you look closely , notice where the transom joins the bottom of the boat. See how sharp and well defined the edge is. This is an absolute must. All edges that come in contact with the water must be sharp. In this case the boat hull came with a rounded edge. If we had put it into service in this condition the water would have "walked" up the transom and produced heavy drag. Looking forward up into the boat you can see the additional foam thats installed , just in case. Also it can be seen where the twin NIMH batteries are stored.

[greenman407]

The steerable outdrive servo is in view as is the RX covered by a homemade alluminum shielded box. Also for RFI protection are the supressors that the motor leads are wrapped around. You can also see the dual lead brushes(hard race type) in their places. These indrive/outdrive units were standard off the shelf Graupner units with variable gearing. The motors however are not. They are Monster Marine motors with variable timing which is important because these race motors can be set to a advance timing setting. They are 23 turn motors for high torque. Using a lower turn motor will increase RPM but reduce power(conterproductive)Just loosen the set screws and pop out the gears , put in a different set and away you go. They finally cracked and fell apart(plastic!) Since they were no longer available what am I gonna do? Throw the boat away?! Right!! To Stock Drive products I went and online, narrowed down the long lists until I found an acceptable substitute. 3.5 to 1 gears were replaced by 3.7 to 1, the best I could do but to get them to fit I had to bush them. Here is the Sabertooth 2x25 covered with a box as well. Time to get back out on the water with it. Oh yes, I dont want to forget to tell you about the Tamiya connecters. GET RID OF THEM. For high amperage work they will disappoint you. In the picture you can see the Deans connecter, just one of several brands of connecters that give you more surface area and a less corrosive prone connection.

[greenman407]

Time for an update. After going to all the effort to try to suppress the heavy RF , the best I could get the range to was about 60 yds. Not enough. Then it hit me. Why dont I take out the futaba reciever and use the Sombra SL-8? I will have an after action report for you soon. Also the X447 berylium copper props, I neglected to tell you, I cut down in diameter years ago to ease up the load on the motors. Well recently with a reduction in speed due to perhaps different gearing I again bought a set of X447 left and right props. But this time I bought them in alluminum.

[greenman407]

All ready to go. Saturday will be the day when you and I will know if the Sombra is as good as we think it is. If all works out Ill be ordering a set of 7 cell(8.4 Volts) Nimh 5000 Mah batts to put in her to give her another Top end gear using 16.8 Volts.

[greenman407]

Didnt make it Saturday. SLAVEDRIVERS!!! Yesterday, after court I swung by the submarine pond and let her rip. Once again, let me extol the virtues of the Sombra SL-8! That was it! Now, no more radio range problems. The Sombra is truly amazing. The next series of tests will be using two cell LIPOs and see what a performance change we see over the two NIMH 7.2 volt packs.

[Buellman1]

Have you tried Lipos out yet? They will make a huge improvement. We have one converted to single brushless and runs extremely fast on just 2 cell lipo.
I'd consider getting a cheap ghz radio set for it too. I've yet to see any radio issues on any of my surface boats.

[greenman407]

Not Yet. This place is brutal plus family problems and too many sub and boat projects in the fire. Not to mention me and my son bought a couple of pellet rifles and weve been plunking around with them. I have no doubt that I will see an improvment in speed. Im already spinning out and swapping ends with her already. If you look at some of the previous pictures that I have posted of her you can see that the outdrives dont stick down in the water too far. Therefore there is not much holding her in the water in the turns.

[greenman407]

Never have put those Lipos in. Maybe soon. I decided to swap out those old motors for some newer ones. The new ones are 21 turn Traxxas 550 air cooled motors. I decided to get rid of the older Monster Marine 23 turn motors because they stopped pulling like they used to. I guess they are getting tired. Over time the magnets lose there strength on these machine wound mods. A handwound motor will have sometimes 4 much stronger magnets to replace the normal two in a machine wind. But , a hand wound is much more expensive. Along with the motor swap, I removed the water cooling system, too much drag.You will notice the fixed endbell on these motors. Definitely not a Mod motor, but they are relatively inexpensive.

[greenman407]

Im going to finish this up so I can test it on Monday. While Im at it we will sneak in a test using two 2s Lipos.