I had my SCX Dual Down shaft lowers blueprinted by Wilson, due to the boat not handling very well and higher speeds. I previously had SC lowers before swapping to SCX DD. With the SC lowers the boat ran like it was on rails and after the swap the handling was terrible. I was referred to Wilson and after talking to Mark and Craig they assured me they could fix my issue. Its amazing how much material was taken off of these during the blueprinting, which almost makes them look the same size as an SC now to the eye. . I was told the lowers had many irregular issues to them after the inspection was done. The bullet is like a hypodermic needle and the skeg is almost razor sharp. They also do a coating which lasts for many years and is a super slick finish, which created a bonus of no more polishing these lowers. They look so much different than the did when they came from Imco. The handling is so much better from docking manners to mid range maneuvering, as well as a full speed run. Also an increase of speed was another small added bonus. I am very pleased with the outcome and would recommend their services to anyone having issues with their lowers. Here's the finished product.

Bencini,

Old pick for reference....?

Thanks. Brad.

Here's the best one I could find. I wish I had taken better pics before sending them off. Seeing them in person is where you can really see the huge difference.

Stock SCX dual Downshaft

Bencini,

It almost looks like there is a distinct "lateral line" running back from the nose point that blends out with the diameter of the main body on yours, where it a basic bullet shape in stock form. I'm always interested in the physics involved, so that is interesting. The stock form lower almost looks like the nose points upward, maybe anticipating a fair bit of trim by the end user, and you didn't need that much trim, and the nose cone was causing lift. Just speculating....

Thanks. Brad.

Both bullets bulky and were pointing different directions, the skegs were varying in thickness and to long, also the leading edge was not very sharp. The body of the lower behind the prop was way to thick, as well as the upper body was way to thick as well. Many irregular areas on these made the handling very bad and caused to much transom lift as well. It almost felt as if they were walking on the props. There was a lot of material removed on both of them.

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How deep are your drives?

4" below currently with 2" spacer, which puts them at standard length, and going to try them as a -2 which will put them at 2" below. Most of the 37 owners have had the best luck using a 1" spacer putting them at a -1. Since everything that has worked on a 37 has been pretty much true to mine when I made the same additions, I believe the -1 will probably be where I end up at. The 37 hull is identical to mine, except shorter on the bow and stern.

Bencini,

In our model boats, we use full wedge rudders; the leading-edge taper propagates all the way to the trailing edge, which is sharp as a razor. This is because anything behind the widest cross section is not only useless for the purpose of the surface, it actually catches turbulence created by the water spoiling behind that widest cross section. This causes the rudder to want to flutter, to the point it will wreck steering servos. I've seen double tapered (leading and trailing edge) rudders destroy really strong servos in just a couple laps on our 1/6th mile course. Think of blowing on a blade of grass between your thumbs as a kid, and what it did to the blade of grass. Well-made turn fins will also incorporate this same theory, but there's way more going on there to get into it. The skegs, for example, were likely parallel, except for a wedge on the leading edge, and this was likely causing some wonky hydrodynamics across the faces of them, that the shop probably eliminated by dragging the taper as far back as the material would allow. The bullet nose is very similar. Even though they technically increase in girth from the point back to the main body, they have a higher degree of attack at the point than they do going back. This creates a similar effect as described with the full wedge rudder, only that turbulence is fed into your props, as well. The shop did their homework, physics and hydrodynamics-wise, and maintained water pressure against the various surfaces as consistent as possible.

As I said, I like digging into the physics of the thing. It's just too cool to actually see real, empirical observation of these forces at work.

Thanks. Brad.