OVM26 Build

[GregS]

I have just begun the build of the BBY Oval Master 26 advanced kit. The kit comes complete with the hull, deck, hatch, hardware, motor, and ESC. Everything needed to build it is included. The only additional things needed are the radio system and batteries. This is my first build.

Although water cooling is not absolutely necessary with the setup I'll be using I plan to install it anyway to keep the motor and ESC cooler and increase their longevity. There is a cooling tube already pre-installed on the ESC. For the motor I'll install brush cooling as well as a water jacket from Offshore Electrics. I'll use a bent brass tube through the transom to pickup the prop wash from the surface prop. The flow will go through the ESC first, then the brush cooling tubes, and finally the water jacket before exiting out the side of the boat.

For batteries I'll use 12 cells - two 6 cell packs in series. I'll use IB cells but am presently undecided about whether to use the 4200 or 3800 or 3600. I'll use Dean's connectors for both the connection of the batteries to the ESC and the ESC to the motor.

PROP - Octura X642
ESC - RC-Hydros Victory 60 amp
Motor - Graupner Speed 700 BB Turbo 8.4V
Radio - Futaba 3PM-FS Magnum FM transmitter, R133F 75 MHz receiver,
S3305 Heavy Duty metal gear servo.

I was unable to upload the picture as the file size was too large. I'll figure this out later and provide pictures in a later post.

[Rex R]

for what its worth... I've seen that a number of folks use 1/8" brass for a pick-up then transition to 5/32" brass inside the boat(including the water dump) reasons given; reduce the presure and water velocity through the cooling system.
re:batts
when last I looked cheapbatterypacks.com had some nice prices on 3600's :) don't over heat the deans plugs when soldering(in partictular the male plugs).

[BoatDoc]

that's a tried and true set up, you shouldn't be disappointed when you're finished.

[SouthJersey-FE]

I am keeping my eye on this one. I have a 700sc and a 90amp Victory that need a home. I was thinking of a mono with a scale look. I have been looking @ outdrive units. Graupner has better pricing but the MHZ units look more sturdy. Hull wise I had the 24" fountain from MHZ in mind. That combo would run 400.00 pluss for just the hull and drive. But I have sworn off abs hulls so I expect to pay a little more.

[Fluid]

Be careful about your choice of hull if you ever intend to race it. The minimum length for a NAMBA LSO boat (Limited Spec Offshore) is 25". IMPBA allows 24" hulls in their similar 12-cell Spec Class.


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[SouthJersey-FE]

Thanks Fluid, Once again you have bailed me out of waisting money....lol. IYO do you think a mono with an outdrive can compete?

[GregS]

The latest is I've cut the hatch in the deck by scoring with a sharp hobby Knife. I drilled small holes in the corners to avoid over cutting. I trimmed and shaped the hatch cover to fit using 100 grit sand paper.

I used medium CA to glue the wooden transom doubler in place. The instructions said to spray accelerator (kicker) to cure the glue quickly. I didn't use the kicker as someone warned me I could easily wind up with a permanent space between the wood and plastic if I screwed up. When I actually went to glue it I understood what the point of the kicker was. The wood didn't bond to the plastic instantly and the plastic would flex away from the wood where I wasn't pressing. By shifting my thumbs around continuously I managed to glue the doubler inplace successfully without any spaces.

The transom doubler needed to be in place for the next step which is to fit the deck to the hull. The instructions mention trimming and sanding the top hull edges and test fitting the deck frequently until the fit is good. Never having done this before I'm not totally sure what is a good fit. I assume this means minimal spaces and gaps.

Also I've been having problems uploading pictures. I got the file size to within the limits by reducing the image quality. However it still didn't upload because of the dimensions being greater than the limit of 1000 x 1000. Not sure how I can reduce the dimensions without cropping the pictures. Any ideas or help here would be much appreciated. Thanks.

Greg

[BoatDoc]

to keep all the pic's nice and simple, i do everything in "paint". you'll be able to do all the down sizing you need in there. if you keep having problems, i can give you my e-mail and you can send me the pics and i'll re-size them for you.

[GregS]

Thanks Boatdoc. I think I've figured out how to do this now. This is supposed to be my first picture before I started assuming it works.

[GregS]

This is the second picture after cutting the hatch and gluing the transom doubler.

[SouthJersey-FE]

Be careful about your choice of hull if you ever intend to race it. The minimum length for a NAMBA LSO boat (Limited Spec Offshore) is 25". IMPBA allows 24" hulls in their similar 12-cell Spec Class.


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I double checked the Fountain Shockwave @ mhzusa. 25.2" just enough

[Fluid]

IYO do you think a mono with an outdrive can compete?The problem with steerable outdrives is they make the boat spin out in turns. On slow RTR and entry-level boats they are okay and give tighter turning radii, but with more speed and power they are a liabillity. They also lose a lot of power through their inefficiencies. You can certainly try one, but my recommendation is to use a non-turning strut, flex cable and a separate rudder.


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[SouthJersey-FE]

The problem with steerable outdrives is they make the boat spin out in turns. On slow RTR and entry-level boats they are okay and give tighter turning radii, but with more speed and power they are a liabillity. They also lose a lot of power through their inefficiencies. You can certainly try one, but my recommendation is to use a non-turning strut, flex cable and a separate rudder.


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After posing that question I found them exploded views of the drives currenty on the market. Lots of drag and extra weight. Again I have saved some money. I keep it up and you will be askin me for a kickbacks :p .
Thanks Man,
Tom

[GregS]

For balancing the prop would a prop balancer give better results than the cheap method of using razor blades? Also which balancer would people recommend? Octura or Top Flite? The Top Flite is a little less expensive. Thanks.

Greg

[BoatDoc]

i use a Top Flite, and i've found that it is just as accurate as some of the very high dollar options out there.

[GregS]

Installation of the motor mount presented some challenges as there were two flat strips of plywood (provided with the kit) to attach the mount to with blind nuts but no flat surface in the hull to glue them to (V-hull). The solution was to build wedges to glue directly to the hull that would provide a flat surface to glue the strips to.

First I made wedges out of 1/4 inch plywood cut to the same dimensions as the mounting strips that came with the kit. When putting the blind nuts in the 1/8 inch plywood strips a couple of problems presented themselves. One was the wood was not thick enough so the tabs of the mount would be against the end of the blind nuts instead of the wood. The other was the base of the blind nut caused an uneven gluing surface on the bottom. I solved the first problem by using another 1/8 inch thickness of plywood that I cut to small squares that the motor mount tabs would sit on. This also solved the problem of the bolt length. For the second problem I used a heavy duty clamp with which I could force the blind nut bases farther into the wood so that I now had a flat gluing surface.

When attaching the mount to my wedges another serious problem surfaced in that the tabs of the mount were bent to different angles. I decided against trying to bend the aluminum for fear it might break. I made one of the small square pieces of wood into a wedge to accomodate the different angle on the one side. I had to decide which tab would be the horizontal one. I chose this based on which one angled the shaft of the motor closest to where the stuffing tube would be.

I spent a fair bit of time test fitting in the hull and sanding the bottom of the wedges so I would have as much surface area as possible in contact with the hull for gluing. I glued it with the motor in the mount so it was easy to line up the motor shaft with the centre of the hull. Being new to this I almost made the mistake of gluing the mount without the motor in it. Likely it would have been off centre and too late to do anything about it. I didn't glue the square pieces under the mount tabs and they're held in place by scewing the mount down on them.

All and all it turned out well.

[Rex R]

looks a little close to the transom, how close is it? methinks I would have put it a tad further forward (closer to the desired cg), well its in now. let us know it turns out please.
rex

[GregS]

It's 2 inches from the mount plate to the transom. Seems a little close to me too but Randy of BBY recommends this spacing for best CG.

[GregS]

Update: The driveline installation is now complete. See attached pictures.

Unfortunately this process did not start well as I drilled the stuffing tube hole slightly off centre even though I measured carefully, made an indentation with the point of a scriber to get the drill bit started correctly, drilled a pilot hole with a small bit before the full sized bit. The drill must have shfited slightly when I started the pilot hole. The hole was only 1mm off but it was enough that the drive shaft would not align perfectly with the motor shaft. The solution was to enlarge the hole to allow proper alignment.

I did not need to enlarge the stuffing tube hole very much. Just a little on the right to allow it to shift over about 1mm. I used the curved front edge of an old dresser in the basement to bend the tubes on. I also used a full 1 foot length piece when bending rather than the small piece supplied with the kit. I had an idea to estimate the angle of the motor shaft by sighting it (while mounted in the boat) against a foot long piece of brass tubing with one end touching the desk surface. Taking measurements of horizontal and vertical distance I reproduced the angle on paper which I compared the tubes to as I bent them. This actually worked as the angle of the tubes I bent was right on. I did a few before I got one that lined up absolutely perfectly.

The tube was held firmly in place by the strut and where it touched the transom hole. I glued it with medium CA first from the inside and then from the outside. There was not much gap to fill. I applied epoxy from the inside to ensure waterproofing and add additional strength. I decided not to make a support because of the tubes short length. All in all I'm very happy with how this turned out. I spent a lot of time fussing over it but it paid off.

Only thing is the setup does not allow the angle of the strut to be changed as the stuffing tube goes into the strut some distance. From the kit instructions the angle of the strut is supposed to be zero degress. I got it as close to zero degrees as my eyes could tell so now I have to hope it works well and any trim adjustments can be accomplished by shifting the batteries and/or adjusting trim tabs.

Greg