Question: Building a Whiplash Sport 40

[SeanKewley]

I'm in the process of building a Whiplash Sport 40 and I was wondering why many put the strut on the inside of the hull. I have built a Whiplash sport 20 and a few other 20 sized sport hydros and the strut seems to work fine mounted on the outside of the transom. What is the logic behind mounting it on the inside for the sport 40?

 

[FloridaScaleBoater]

Rules

from the IMPBA rule book for sport-40 boats specs

See rule #7

Boat Specifications

1. Boat must be inboard powered.

2. Hull must be a three (3)-point hydroplane configuration and resemble a limited or

unlimited hydroplane design of past or present, except outrigger, modified outrigger,

tunnel, or canard hulls are NOT permitted.

3. Boat must have a name, sponsor's name, logo, and/or a racing number affixed to hull

(a local, national, or fictitious sponsor name is acceptable).

4. Hull shall be a minimum of 35 inches and a maximum 40 inches in length.

5. If the bow is recessed behind the tips of the sponsons, that recess shall be no larger

than 25% of the overall length of the boat.

6. Boat must have a driver and/or simulated enclosed cockpit.

7. No part of the strut may protrude behind the transom of the boat, or have a width

greater than 9/16 inches or a length longer than 3 inches.

8. See Sport Hull pictorial for clarification

In NAMBA the quick down & dirty is

SPORT HYDROPLANE

Revised 2/19/08

8. The propeller drive dog may be one drive dog length behind the transom of the boat.

 

[SeanKewley]

I see. Thanks for helping a noob Rick.

Do most use blind nuts on the outside when mounting the strut on the inside? Is there a preference for mounting the strut on the bottom VS. the inside of the transom?

 

[LarryConrad]

I use stainless steel machine screws with the beveled heads and counter sink the holes so the screw heads are flush with the bottom of the boat.

 

[FloridaScaleBoater]

Mounting the strut bracket to the inside if the transom is alot easier to do, just remember to seal around the strut were it goes through the hull.

I use finish washers with flat head screws to make it look a little nicer from the outside

 

[LarryConrad]

There's more than one way to skin a cat...'er strut a boat.

 

[glenng]

There's more than one way to skin a cat...'er strut a boat.

Right you are Larry-check out Lenny Blakes struts(Rum Racing .com) mounted to transom but blade goes out the bottom of the boat-NAMBA legal as long as the drive dog is under the transom.

Glenn

 

[FloridaScaleBoater]

Actually the rule reads:

8. The propeller drive dog may be one drive dog length behind the transom of the boat.

Not under the Transom

 

[SeanKewley]

Out of curiousity... What is the reasoning behind this rule? Scale appearance?

 

[FloridaScaleBoater]

Not really sure,

I do know that it has been tried to get it changed a few times, and it gets shot down every time???

 

[SayMikey]

Not really sure,

I do know that it has been tried to get it changed a few times, and it gets shot down every time???

Sport 40 racing is a tuners class. Sticking the strut behind the transom takes away from it being a tuners class. That one drive dog length will net 4-5 mph trust me I know been there done that. This class is sooo competitive with boats going into the low 60s on a regular basis,nothing like 6-7 hitting the line together then it becomes a drivers class. Most fun class in racing next to scale. These are my opinion

 

[SeanKewley]

I'm ready to buy the fuel tanks. The instructions say that 2 x 8oz Sullivan SO8 will fit... problem is I don't see a part #SO8 offered by Sullivan.

Link to tanks: http://www.sullivanproducts.com/ProductIndexMainFrame.htm

Anyone know which tank is being referenced that will fit in the Whip 40?

 

[SayMikey]

I'm ready to buy the fuel tanks. The instructions say that 2 x 8oz Sullivan SO8 will fit... problem is I don't see a part #SO8 offered by Sullivan.

Link to tanks: http://www.sullivanproducts.com/ProductIndexMainFrame.htm

Anyone know which tank is being referenced that will fit in the Whip 40?

s08 slant oval 8 oz

 

[SeanKewley]

Thank you Mike.

 

[Michael Costanzo]

Not really sure,

I do know that it has been tried to get it changed a few times, and it gets shot down every time???

Sport 40 racing is a tuners class. Sticking the strut behind the transom takes away from it being a tuners class. That one drive dog length will net 4-5 mph trust me I know been there done that. This class is sooo competitive with boats going into the low 60s on a regular basis,nothing like 6-7 hitting the line together then it becomes a drivers class. Most fun class in racing next to scale. These are my opinion

amen to that! unfortunatly none of that down here. muck boat i won div years ago still sitting on the shelf). :angry:

 

[RaceMechaniX]

Rick,

There are some pics in my gallery of the whip strut mounted. here is one of them:

I sent Walt Barney some drawings for stainless tanks for the Whip sp40 and they fit perfectly. I am sure he can fab some up for you.

Tyler

 

[SeanKewley]

Rick,

There are some pics in my gallery of the whip strut mounted. here is one of them:

I sent Walt Barney some drawings for stainless tanks for the Whip sp40 and they fit perfectly. I am sure he can fab some up for you.

Tyler

Thanks for the pic. I tried looking in your gallery, but I only saw pics for the gas whip. Could you post a link to the sport 40 pics?

 

[RaceMechaniX]

Yup, here ya go: Whip Sport 40 Gallery

 

[SeanKewley]

Yup, here ya go: Whip Sport 40 Gallery

What rudder and strut are you using on your whip40? Thanks for the link to the pics.

 

[RaceMechaniX]

Speedmaster 21 rudder with short offset and a 3/16" square bottom strut. I believe its what Brian recommends in the manual.

Tyler