Help with Bandit Tunnel

[Greg Mortlock]

Hi All

Ive just recently aquired a Bandit Tunnel,

This is a very nice looking boat i must say.

This was a new Fibreglass Hull and hasnt seen water yet other than our pool for the pic,see my gallery my gallery

Ive set this up with a 7.5K&B,8oz Slant oval fitted to a cradle which ive mounted and also a 2oz Hopper,

The bottom of the sponson at the rear is stepped forward to 6" and the edge of sponson in the tunnel is very sharp to about 10" forward.Hopefully this info will help you guys with this hull.

Questions i have are cog,props,engine heights whatever info i can get greatlty appreciated.would the setup for this be much different from my 7.5hotshot.

thanks

Greg

 

[Jack Garcia]

Hi AllIve just recently aquired a Bandit Tunnel,

This is a very nice looking boat i must say.

This was a new Fibreglass Hull and hasnt seen water yet other than our pool for the pic,see my gallery my gallery

Ive set this up with a 7.5K&B,8oz Slant oval fitted to a cradle which ive mounted and also a 2oz Hopper,

The bottom of the sponson at the rear is stepped forward to 6" and the edge of sponson in the tunnel is very sharp to about 10" forward.Hopefully this info will help you guys with this hull.

Questions i have are cog,props,engine heights whatever info i can get greatlty appreciated.would the setup for this be much different from my 7.5hotshot.

thanks

Greg

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Greg,

Thank you for purchasing the Bandit "killer" tunnel. I am the feller that designed that boat.

To start with, as with all tunnelhulls, make sure that all surfaces on the bottom of the sponsons are parrallel to each other. Warped sponsons are the downfall of all tunnelhulls.

Here is an article I wrote pertaining to the "blueprinting" of sponsons.

TUNNELHULL,TUNING THE SPONSONS:

If you want the most from your tunnelhull and are willing to take the time to do it, there are some easy tricks you can do to enhance its performance. Note: This next part of preparing your boat should be done before you have applied any paint. It involves "tuning" the sponsons. To tune the sponsons, here are the tools you'll need. A straight edge such as the steel ruler on a carpenters square, some 120 or 180 grit sandpaper, and some 320 and 400 grit wet or dry as well. Make yourself a sanding block of 1" thick pine that's 10" or 12" long by 3" wide. Using contact cement, glue a strip of the 180 or 120 grit sandpaper to the sanding block. Don't just wrap the sandpaper around the block it won't be flat enough. You will also need a small, sharp, fine tooth flat or half round file.

Your engine is the most important part of your boat. It transfers the horsepower to the prop that pushes the boat forward. How fast depends on how much horsepower the engine is generating and how well you have set up the boat. One part of setting up is to

make certain that the hull bottom is correct. Are the riding surfaces flat and true? Are the edges sharp? Are the sponsons true and equally flat?

These irregularities occur mostly on fiberglass hulls. Polyester in particular. (Fiberglass Resin). Epoxy resin hulls are not as susceptible as polyester, but its good practice to check the bottoms on all boats, even wood and new boats. This is part of fine

tuning that allows you to get the most out of your boat hull. It's important that sponsons on tunnels are equal horizontally. To check, place the hull, sponsons down, on a perfectly flat board. (It's important that the board is PERFECTLY FLAT, or else you

will get a wrong reading.) Position the hull so that you can see any light that may show through, indicating that the sponsons are not equal. These must be made equal to start with. Using the sanding block, sand equally on both sponsons one at a time, concentrating on the lowest part until you are satisfied that they are both flat with no light showing through. Next thing to check for, is an irregularity on the riding surfaces. It may be a bow (Rocker), or a dish, (Hook). Place the straight edge longways on the sponsons, and slide it from side to side. As before, position the hull so that you can see light that may show through between the straight edge and the sponson. Hooks will appear mostly near the transom. Don't try to remove a hook until you have first sanded the rest of the bottom flat. If there is still any indication of a hook, roughen the area by sanding, and fill it in with putty made of epoxy and micro balloons. Re-sand when the putty has hardened, making certain that this area is equally as flat as

the rest of the bottom. Another area that needs attention are the edges, such as the back bottom edges, steps, and inside sponson edges. These should be sharpened. The reason for making edges sharp, is that water tends to cling to rounded surfaces, causing

friction. By sharpening, you are allowing the water to break away cleaning, thus adding to your boats speed and maneuverability. Use the file to very carefully sharpen all of the steps.

After you have straightened, flat sanded, and sharpened, you are ready to do the finish sanding. Use the 300 grit wet or dry sandpaper to smooth the rough areas. (Use the sandpaper wet). Now do your finish sanding with wet 400 grit. I may go overboard, but I follow the 400 grit with 800, until I get a glaze.

Good luck and good boating

 

[[email protected]]

I've owned a few Bandit boats and they are awesome. I opened my instruction manual fo the Killer 7.5 and the one thing Dorrien did not put in the book was CG location. Since I no longer own a 7.5 my personal notes told me my CG was between 9 to 9 1/4.

As for props for a stock 7.5 try:

X447 two & three blades

X448 two blade

X450 two blade

The equivelent in the 235 series on up will work but I had best luck w/the Octura props.

For some reason I couldn't get your pictures to open larger so I'll ask you:

Is your radio box as far forward as possible? Are the servos far back so that the battery and receiver are as close to the nose as possible?.

These are important to help w/the balance and getting the boat to run best

Can you swap the 8oz for a 12oz tank?

8oz is too smallfor a 7.5, just as you'd be getting going you'll be coming in to refuel.

Don't forget to add floatation to the top of the cowling

Have fun and Good Luck!

 

[[email protected]]

Hopefully Jack can give you the right CG, I just remember, mine had a tuned pipe on it.

I like the hopper tank mount you made, looks really nice. Are those your original Villians, very nice as well.

On the engine height the Bandit's have a much different ride attack then say a Maus or an Aerotech. They don't look like your flying a kite and the nose won't be pointing way up. Try the motor at 1/8 of an inch above the rear transom and work down or up from there.

 

[Jack Garcia]

I've owned a few Bandit boats and they are awesome.  I opened my instruction manual fo the Killer 7.5 and the one thing Dorrien did not put in the book was CG location.  Since I no longer own a 7.5 my personal notes told me my CG was between 9 to 9 1/4.
As for props for a stock 7.5 try:

X447 two & three blades

X448 two blade

X450 two blade

The equivelent in the 235 series on up will work but I had best luck w/the Octura props.

For some reason I couldn't get your pictures to open larger so I'll ask you:

Is your radio box as far forward as possible?  Are the servos far back so that the battery and receiver are as close to the nose as possible?.

These are important to help w/the balance and getting the boat to run best

Can you swap the 8oz for a 12oz tank?

8oz is too smallfor a 7.5, just as you'd be getting going you'll be coming in to refuel.

Don't forget to add floatation to the top of the cowling

Have fun and Good Luck!

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Thanks for the imput Rodney.

Greg, Rodney is right on the C.G. and props. ( 9 to 91/2") from the sponson transoms is good .

 

[Greg Mortlock]

Hi Jack & Rodney

thanks guys for that info very helpfull,ill put all those things into practice,

Jack whats the idea with sponson bottom design,

On my hotshot the bottoms are flat for about 9" and the bandits arnt.

if you look along the sponson bottom from the front to rear it is all the same and when you get 6" from the transom the sponson bottom is a different height do i work both these heights or just the 6" from the rear i can send a pic if im not clear enough.

Rod im running a 10oz with hopper in my hotshot and i thought it was big so i went the 8 can still change though,

Radio box is a far forward as possible,1/4scale servo at theback of box and batteries are up the front.

thanks

greg

 

[Jack Garcia]

Hi Jack & Rodneythanks guys for that info very helpfull,ill put all those things into practice,

Jack whats the idea with sponson bottom design,

On my hotshot the bottoms are flat for about 9" and the bandits arnt.

if you look along the sponson bottom from the front to rear it is all the same and when you get 6" from the transom the sponson bottom is a different height do i work both these heights or just the 6" from the rear i can send a pic if im not clear enough.

Rod im running a 10oz with hopper in my hotshot and i thought it was big so i went the 8 can still change though,

Radio box is a far forward as possible,1/4scale servo at theback of box and batteries are up the front.

thanks

greg

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Good question Greg. The step of course is there for speed, and the reason it's only 1/32 " deep is so's the boat won't ride too nose high. Although it does like to ride fairly high. This is the reason why you should run the engine at zero degrees or minimum of 2 degrees nagative. (points the nose up) I set the engine so that the bottom of the propshaft bullet on the lower unit is minimum 1/16" above the bottom inside of the sponson. I should add a bit of sponson tuning info here. File away the roundness behind the step. You want a sharp edge on the step. This increases speed . One more filing job, the relief on the inside of the sponson in front of the step ended up being roundish in manufacturing. This needs to be filed flat at a 45 degree angle to the inside of the sponson, and should be 3/8 " wide. This makes for better turning. Hope we've been helpful here Greg. And again, thank you Rodney for your imput.

 

[Greg Mortlock]

Hi Jack

Thanks for the info very helpfull,

good to know why the step in the sponson bottoms is there,

Jack ill look at all those points you mentioned and see how it goes im planing on running it the 12th june at our next meet so ill let you know how it goes.

thanks again Rodney as well.

greg

 

[Greg Mortlock]

Hi Jack

Thanks for the info very helpfull,

good to know why the step in the sponson bottoms is there,

Jack ill look at all those points you mentioned and see how it goes im planing on running it the 12th june at our next meet so ill let you know how it goes.

thanks again Rodney as well.

greg

 

[theringwah2002]

Hey Greg,

the new boat looks great. I am VERY jealous.

Mate I might see you guys on the 12 with the old boat.

Mark

You are correct, I would probbly be a good reference for the buying boat overseas!!

 

[james irwin]

Hi Jack & Rodneythanks guys for that info very helpfull,ill put all those things into practice,

Jack whats the idea with sponson bottom design,

On my hotshot the bottoms are flat for about 9" and the bandits arnt.

if you look along the sponson bottom from the front to rear it is all the same and when you get 6" from the transom the sponson bottom is a different height do i work both these heights or just the 6" from the rear i can send a pic if im not clear enough.

Rod im running a 10oz with hopper in my hotshot and i thought it was big so i went the 8 can still change though,

Radio box is a far forward as possible,1/4scale servo at theback of box and batteries are up the front.

thanks

greg

101254[/snapback]

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Good question Greg. The step of course is there for speed, and the reason it's only 1/32 " deep is so's the boat won't ride too nose high. Although it does like to ride fairly high. This is the reason why you should run the engine at zero degrees or minimum of 2 degrees nagative. (points the nose up) I set the engine so that the bottom of the propshaft bullet on the lower unit is minimum 1/16" above the bottom inside of the sponson. I should add a bit of sponson tuning info here. File away the roundness behind the step. You want a sharp edge on the step. This increases speed . One more filing job, the relief on the inside of the sponson in front of the step ended up being roundish in manufacturing. This needs to be filed flat at a 45 degree angle to the inside of the sponson, and should be 3/8 " wide. This makes for better turning. Hope we've been helpful here Greg. And again, thank you Rodney for your imput.

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hey jack . you may want to tell them that we found we can control the nose height by reducing the height of the step . guys , i will go on record and tell you all , i love this boat . god bless

 

[Jack Garcia]

Hi Jack & Rodneythanks guys for that info very helpfull,ill put all those things into practice,

Jack whats the idea with sponson bottom design,

On my hotshot the bottoms are flat for about 9" and the bandits arnt.

if you look along the sponson bottom from the front to rear it is all the same and when you get 6" from the transom the sponson bottom is a different height do i work both these heights or just the 6" from the rear i can send a pic if im not clear enough.

Rod im running a 10oz with hopper in my hotshot and i thought it was big so i went the 8 can still change though,

Radio box is a far forward as possible,1/4scale servo at theback of box and batteries are up the front.

thanks

greg

101254[/snapback]

​

Good question Greg. The step of course is there for speed, and the reason it's only 1/32 " deep is so's the boat won't ride too nose high. Although it does like to ride fairly high. This is the reason why you should run the engine at zero degrees or minimum of 2 degrees nagative. (points the nose up) I set the engine so that the bottom of the propshaft bullet on the lower unit is minimum 1/16" above the bottom inside of the sponson. I should add a bit of sponson tuning info here. File away the roundness behind the step. You want a sharp edge on the step. This increases speed . One more filing job, the relief on the inside of the sponson in front of the step ended up being roundish in manufacturing. This needs to be filed flat at a 45 degree angle to the inside of the sponson, and should be 3/8 " wide. This makes for better turning. Hope we've been helpful here Greg. And again, thank you Rodney for your imput.

101268[/snapback]

​

hey jack . you may want to tell them that we found we can control the nose height by reducing the height of the step . guys , i will go on record and tell you all , i love this boat . god bless

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Thanks for chiming in here Jim. Reason I did not mention that is that It's quite an undertakng for a person who may be inexperienced sanding away a lot of material and still keep the trueness of the riding surfaces. Case in point, I advised a boater to do this, he had handling problems after that, turns out that he really did not know what he was doing and added imperfections to the riding surfaces.

Greg, If you think you can tackle the job, go for it ma man. I for one never had the need to perform that modification. Not saying that Jim is wrong.

 

[Greg Mortlock]

Hi Guys

Thanks Jim for the info as well,

At this stage ill just make sure the bottoms are flat and true as Jack said and give it a go at that.

 

[Josh Stollfuss]

Would the irregularities in the sponsons cause the hull to hook in turns? I have a Killer 33 that seems to want to hook at times.

Josh-

 

[[email protected]]

Josh,

The irregularities of the Bandit won't cause it to hook. What could be doing this is a couple different things:

1) Weak steering servo or not centering possibly a weak battery

2) Too much slack in the cables for steering

3) Check to see if the motor/radio are aligned straight.

A lot of times servos don't center so when your steering you'll oversteer to compensate which could cause hooking.

Hope it helps. The other guys can probably give you better advice but this is how I fixed my boats when they hooked.

 

[Jack Garcia]

Josh,
The irregularities of the Bandit won't cause it to hook.  What could be doing this is a couple different things:

1) Weak steering servo or not centering possibly a weak battery

2) Too much slack in the cables for steering

3) Check to see if the motor/radio are aligned straight.

A lot of times servos don't center so when your steering you'll oversteer to compensate which could cause hooking. 

Hope it helps.  The other guys can probably give you better advice but this is how I fixed my boats when they hooked.

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Good points Rodney. There is a little more advice I would like to offer, and that is to make sure that the engine is not trimmed under too much. Please refer to the part where I mention flattening the 45o angle on the sponson. As mentionedbefore, it should be flat, not roundish.

 

[Greg Mortlock]

Jack

Just with regards to the 45 Deg angle,

if i measure from the rear of the transom forward the inside edge is sharp to about 10 1/2 " then the radius goes forward from there,the more it goes forward towards the tips the sharper it gets again,is this the area your talking about,if so

my question is how far forward from the sharp edge do i need to make 45 deg,all the way to the tips or part there of.

Or do i chamfer from the 1/32 forward.

Jack i put a pic of this area in my gallery to show you.the pic shows the 1/32 step and the radius change from sharp

Jack if i was running this as a boat not for racing but for enjoyment as theres no one here racing 7.5 tunnels would this change be necessary.(the 45deg) or should i do this to get a better boat all round.

I appreciate all the help

thanks

greg

 

[Jack Garcia]

Jack
Just with regards to the 45 Deg angle,

if i measure from the rear of the transom forward the inside edge is sharp to about 10 1/2 " then the radius goes forward from there,the more it goes forward towards the tips the sharper it gets again,is this the area your talking about,if so

my question is how far forward from the sharp edge do i need to make 45 deg,all the way to the tips or part there of.

Or do i chamfer from the 1/32 forward.

Jack i put a pic of this area in my gallery to show you.the pic shows the 1/32 step and the radius change from sharp

Jack if i was running this as a boat not for racing  but for enjoyment as theres no one here racing 7.5 tunnels would this change be necessary.(the 45deg) or should i do this to get a better boat all round.

I appreciate all the help

thanks

greg

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Greg,

Only file where the radius starts. And keep it 45o X 3/8" wide for at least 4", then start diminishing the 3/8" width going towards the tips. Greg go ahead and do it just for experience and to get a better boat all around as you say.

Have a good day mate,

Jack

 

[Josh Stollfuss]

Thanks, I think the hooking problm is from weak batteries. I'm going to check my sponsons as described also. Thanks for the help!!!

Josh-