Hot Shot Sprint Set Up Tips (if you would)

[Thompy]

I've had this tunnel for about 2 months, but just got it out in the last few weeks because of the nice weather here in Ohio. I've been communicating with ob nut regularly, but if I'm not mistaken he's on a business trip (thats the last I heard from him) so I thought I'd hit you guys up for some info. I'm only running 20% Wildcat so I'm not getting crazy speeds but it tends to hook a tad in the corners. The motor runs great, its an older K&B black carb 13 mm crank, but I'm needing some good starting points for the set up. Here's what I've got. Spoons and prop shaft are parallel, I've got the thrust angle at 0 degrees, I tried setting it up with alot of thrust angle but it was running extremely nose up. It tends to only hook in water like glass, yet wants to blow over with a little chop. No weight in the front, was wondering if you guys had a clue to the weight that needs to be added and the CG for this boat.

I broke a flex shaft two days ago, but I've got two Lawless shafts on order from precision boats so they should be here in next week. Any info on this boat would be appricated. I'm not in it to race, just wanna get acquainted with the sport so I can race.

 

[Marty Slater]

the one i had needed about 6oz in the radio box.1/8 to 3/16 center of prop shaft above sponson bottom with an x440. an the nose will tend to be a little higher then most newer tunnels. its a short boat an a Rocker to boot that is if you set it on a flat surface the sponsons are not flat they look like grandmas rocker

Marty ABS hull not wood

 

[Jerry Dunlap]

You'll definitely need to ad weight to the front. I haven't run one in years, but seems like I was between 4 and 6 oz on the sponson tips.

You might want to consider adding "stumble blocks" under the the front of the boat if it wants to hook.

JD

 

[dave roach]

I have been running the hot shot sprint for about 16 years in stock class and I don't add any weight to the boat. It is in the set up and what prop to run.

Dave Roach

 

[Thompy]

I'll second the rocker ideal. I was looking at it when I first got it and was thinking something wasn't right. But I'll take your guys' word for it. I'll look into putting weight in the nose when I can get the motor put back together.

What effect would lowering and raising the prop have, besides making it cavitate or lug the motor? More lift, less lift?

 

[Jerry Dunlap]

Raising the prop will less the amount of lift.

JD

 

[Thompy]

Thanks, JD. Never hurts to get advice from a seasoned professional and master builder/designer. I've always wondered, did you take any schooling of any kind in design? Or is your talent natural, with a little bit of passion for the sport?

 

[Jerry Dunlap]

re: did you take any schooling......

In high school I took mechanical drawing and boat drawing. There's a JD interview posted on IW that gives some background on my model boating endeavors.

JD

 

[Thompy]

I'm sure you guys have purchased from precisionboats.com or race with the guys that run the store so I figured I'd ask if this is normal. I ordered some flex shafts 6 days ago, and I haven't heard anything from them. I've sent them two emails with no response, and on their site it says the order is pending. Is it pending as far as getting ready to ship out, or is it in transit? I'm dying to get back to this boat, and I'd like to know whats going on. I don't doubt that these guys are honest, and not just taking me for my money I'd just like to know whats taking so long.

 

[Jerry Dunlap]

I believe Tim Fulton was once again undergoing treatment for cancer.

JD

 

[Ronald van Essen]

Thanks, JD. Never hurts to get advice from a seasoned professional and master builder/designer. I've always wondered, did you take any schooling of any kind in design? Or is your talent natural, with a little bit of passion for the sport?

Maybe JD read the famous book:

Take a look:http://www.aeromarineresearch.com/stbd2.html

Ronald.

 

[mark james]

I run a sprint for yrs and was my first tunnel boat..I ran a stock k&b with a RED carb on it and it liked a x437/3 blade prop..I also tured up the inside edges on the hull to make it handle better and noticed it!

I did try to also run a mod.rossi motor on it but it just doesnt like it..I boat is to short .

I also use tape weights inside (front)of the radio compartment to help keep it on the water.(4oz.) B)

 

[Thompy]

Man, I didn't mean to hit on a touchy subject like that. If thats the case I wouldn't mind if I ever got the shafts and they can have my 20 bucks as a donation for his treatment. I was really hoping I wasn't going to get an answer like that. I was hoping they were backed up with so many orders for the upcoming racing season. If any of you talk to him, wish him luck.

Thanks for the tips on the boat, all info on this end is very appriciated. I see on ebay there is a Red carb, is there that much of an improvement from the old stock black carb, and would it be considered a decent performance gain if I stuck one on there?

 

[Thompy]

One more thing. Should I cut off the water flow a little, or let any water flow at all? When I bring the boat in, the head is as cold, or colder then when I launched the boat. I'd say the water temp is around 63 degrees (thats what I'm getting on my "bass boats" electronics) and air temps around 70 give or take everyday, but I'm not fimilar with how warm these motors should run. If there's any fisherman in here 65 degree's is the magic number around these parts for the bass to start spawing, so I can pull double duty, catch a few largemouth and run the tunnel if they're not biting.....

 

[Jerry Dunlap]

The best carb for the K&B 3.5 is probably the gold carb. The red carb can be a bit tricky when attempting to set the needle. But, the red carb would provide some performace gain over the black.

JD

 

[Thompy]

I see truing the hull came up in the post, and it got me wondering. If I were to do this how would I go about it, and what would need to be trued up if anything?

 

[Thompy]

Any comments on truing a hull? Or if I should restrict the water passage to get the temp of the motor up?

 

[RodneyPierce]

Any comments on truing a hull? Or if I should restrict the water passage to get the temp of the motor up?

Thompy, I will help you out, since knowbody else seems to want to right now anyways. Im also new to tunnels, but ahve talked to a few of the OG guys on here including Irwin, and here is what I belive they mean by "trueing" up the inside of the sponsons. Basically, add a sheet of thin ply the length of the sponsons, let it overhang a 1/6th of an inch or s. After thsi is dry, sand it level with the inner edge of the sponsons, and use a filler of some sort to fillt eh small gap. I like bondo glazing and spotting putty, but others prefer regular bondo, or some even use epoxy. Again, then sand this down. You want a nice sharp edge on teh inside of the sponson, this will help the boat in turning instead of skipping through the turns. Someone PLEASE correct me if this is not waht you are talking about.

 

[Jerry Dunlap]

That's pretty much how you true up sponsons.

With the ABS Sprint, make sure both sponsons are touching evenly when placed on a flat surface.

JD

 

[Thompy]

No thats exactly what I'm talking about. I've just seen the idea getting thrown around here and was wondering what it was all about. I'll give that a try when I get my hands on some wood. I see that raising the temp of the motor does wonders as well. I'm not used to having to heat the motor up, running 10th scale stadium trucks you really have to worry about keeping the temp down, rather than raising it. I would just like to know a good way to restrict the water flow, so I don't end up flash heating the water to steam, then I'd be in alot of trouble.