Sport 20 Under construction

[Brian MAhoney]

Heres a couple of pictures of the Whiplash inspired sport 20 I am building.

 

[Brian MAhoney]

top view

 

[Brian Blazer]

Cool, how long is it? How wide is it? I can't wait to see how it runs. Eventually I will scale down the design too and build one. Great job!

Brian

 

[Brian MAhoney]

The boat is about 30 inches long. Basically I started by multipying the Whiplash 40 by 5/6 then adjusting a little from there utill it looked right.

Tub section is 3.5 inches wide, to fit a mount made by Mike Hughes. The mount will bolt through the bottom of the hull. Sponsons have 3 degrees diheadral. Hardware will be a bunch of recycled bits and pieces I have around.

If this works OK I wil build another putting more effort into getting a lighter structure.

Will update this as I progress.

Brian Mahoney

 

[Brian MAhoney]

Just a quick update as to measurements.

Length 30 inches

Width 15 inches

"Tunnel" width 8 7/8 inches

Transom width 7 1/4 inches

I fitted the deck last night will try and post another oicture or two tomorrow or Monday.

Brian Mahoney

 

[Brian MAhoney]

Here's another pic with the deck.

Weight with engine, tanks servos strut and rudder is currently 4 lb.

If I can do this well then anyone can. If you have ever considered building a wooden boat then have a go. Brian Blazer has some excelent plans available.

Brian Mahoney

 

[waterbug]

One question Brian { both Brians} You have my attention !!! Are the steps on the front sponsons the same size ?? and are the sponsons the same size ?? on the 40 and on the 20. I mean I know there is a difference between the 40 & 20 .

On the picture of the 20 upside down the left looks like it is different than the right.

:blink: :blink: :blink: :blink: :blink: :blink: :blink: :blink: :blink: :blink: :blink: :blink: :blink: :blink:

I love my tunnels but the sport 40's and 20's intrigue me very much !!!!!!! 40's the most. I live to scratch build !!!

 

[Brian MAhoney]

Waterbug

On my Sport20 I have made the left and right sponsons mirror images of each other. My photography may be to blame for any for any apearance of asymetry.

Brian Blazer produces an excelent Sport40 plan and kit. It would be a good place to start with these types of boat.

Brian Mahoney

 

[Shnick]

Hey Brian, what rudder/strut setup are you going to use?

Shnick

 

[Brian MAhoney]

Rudder and strut are two that I have used on an eagle SG. Got them from Prestwich Models here in the UK. Hope to get the boat wet again soon, am changing from square drive to collet so need to replace the stuffing tube.

Brian

 

[Brian MAhoney]

here's a picture showing strut and rudder.

Brian

 

[Brian MAhoney]

Had a good run with the Sport20 yesterday. I am now running a stock CMB 21 longstroke, 10% nitro fuel and using an x440 prop.

With a little adjusting of needles and adding a someangle to the strut I had it launching easy and running about 40 mph. The water was quite choppy and I was surprised that the sport hydro would run at all.

Now I need to get hold a few alternative props (thinking of a 1440 and 1640) and maybe a speedmaster hydro strut and see if I can find a better setup than I have already.

Brian Mahoney

 

[Brian MAhoney]

Update

Still on the x440 prop. Put the GPS on and ran 42 mph.

I can only mout the GPS (Garmin Etrex) in the middle of the hydro, and wandered if it would plane with the added weight and rearward C of G. Was surprised that the Whiplash still launched easily and had little diffculty getting on the pipe. Could detect no difference in the corners.

Should have the new srut and props for next weekend, hope to be at mid to high 40s.

Brian Mahoney

 

[Shnick]

Good stuff Brian, couple of questions...

1. Looking at the prop chart, X440 and 1440 are identical as far as dimensions go, what structural difference makes the x440 a lifting prop?

PROP         SIZE                  PITCH            SHAFT

1440      40mm  1.57"  1.4 x 1.57 = 2.198  .187

X440     40mm  1.57"  1.4 x 1.57 = 2.198  .187

2. Have you decided on a paint scheme?

Shnick

 

[Brian MAhoney]

Shnick

1 props, the x440 is a low lift prop, 1440 and 1640 high lift. I'm no expert on props, sharpen and balance is about as good as I get.

I currently have a couple of degrees incidence on the strut to lift the back end, I am hoping that with the high lift 1440 and 1640 I can have the srut parrallel to the bottom of the boat and possible gain a little speed.

I will also be trying a flat bottomed strut, again to lift the back of the boat.

From experience with 21 boats a small change on the boat can make a big change in terms of performance, hopefully with a few props and a couple of struts to test I can find a set-up that really suits the Whiplash and get close to 50 mph.

2 Paint is my biggest weakness, so the boat mak end up with just the epoxy finish, may use an aerosol and paint the boat yellow, I liked the look of Don's DeWalt boat.

Brian

 

[Pennywizz6]

Wow, you people have timeo yours hands, well so do I but umm i like pre built monos :lol: . Its looking good though. Make sure its perfectly smooth no bumps ridges or nothing. Must I reccomend, for your glueing needs (if you have more gluing to do) get gorilla glue, 100% waterproof and wickedly strong, go to menards, they will have some, sometimes even on the ittle rack with cool gadjets they will have a small 4oz of it. Kudos to Mr.Gorrilla not you brian, the person who makes the glue, but kudos to you anyways!!

Phil :lol: :wacko: -_-

 

[Don Ferrette]

"2 Paint is my biggest weakness, so the boat mak end up with just the epoxy finish, may use an aerosol and paint the boat yellow, I liked the look of Don's DeWalt boat."

Definitely easy to see on the water & a pretty basic paint scheme too!