3.5 Tunnel SAW record

[Tommy Lee]

Mark-

The "thingies" on the red boat are just something I wanted to try. I was having trouble with the boat coming off the water over 45mph and I put these on at the lake one day. It didn't help the problem but they didn't hurt the way the boat ran and I thought they looked kinda trick so they stayed. After Rod saw the boat run, he felt they were helping the boat in the turns by sucking the inside sponson down on the water-makes sense to me.

 

[Tommy Lee]

Gene-

You ask about the record boat- the boat is not light- the bare boat weighs 2lbs.14ozs.and I think ready to run less fuel is just over 5lbs. but it is very strong. Remember they hit the water really hard at 60+. The sponsons are 26&1/2 inches- the tunnel floor is5&1/4 inches wide& 1/2 inch deep. It has what I will call primary& secondary sponson pads and it would take me all night to explain this so you probably need to see a picture. the secondarys are 2&5/8 inches wide and the primarys are 1&3/8 inches wide. The boat is 11&1/2 inches wide overall and the transom is inset 1&3/4 inches. I did this to help with the C.G. On a normal boat this would not work but this thing does not have any problem "airing out". That's about it for the boat, I used a standard K&B lower unit with an H-4 prop cut to 42 mm dia. O'donnell 50% fuel and good air!

 

[Slideblues]

Mornin Gang,

Tommy, the tunnel area of our hulls are very close in size, I just called Mike Z. couple nites ago and we talked about it some. Mine, the tunnel floor was 5 5/8" wide and 5/8 " deep, sponson length 28" Weight with fuel was just over 4 lbs, the outboard for mine was a Nova 2000 on a K&B foot and I also ran a H-4 dia reduced, transom inset was 1 1/2"

I know what you mean about try'n to explain something in text, I have a hard time with that too.

The primary and secondary sponson pads are very interesting to me, maybe Rod could draw it out and post it if you cant get a pic online ?

This is great info, and thank you for posting

Gene

 

[Jimmy Whitbeck]

So why is it every one want's a boat built Light for saw? as I tried this light tunnel and the darn boat was too light and could not keep it on the water the right side up! Is thare some thing i missed?

Jimmy

 

[Jerry Dunlap]

Re: "is there something I missed?"

Probably not.

JD

 

[Slideblues]

Hi Jimmy,

Mine was too lite, it ran well but at the top end of the run it was a handfull to control.

Razor edge stuff,

Gene

 

[Jimmy Whitbeck]

Hi Jimmy, Mine was too lite, it ran well but at the top end of the run it was a handfull to control.

Razor edge stuff,

Gene

i ges I was not the only one thinking lite was good!! just to find out it can not be good all the time.

Jimmy

 

[TimD]

I got this center section ready to go for testing out ideas, was wondering bout the sponsons,Gene

Gene,

is that cetre section the same design as the one you ran before and destroyed?

Tim.

 

[topfuel443]

If I could only get Gene to try out my center section.......

~ James

 

[Tommy Lee]

J. Whitbeck-

The difficulty with building a tunnel for big speeds is that you must design the boat around what it is going to weigh and how fast you are trying to go. I do not think ultra light weight is the way to go for s.a.w. speeds with a tunnel.

 

[GTR]

Hi Guys

My observation would be that weight really only affects the speed with which something accelerates and not it's terminal speed. Once the tunnel is flying if properly designed/balanced etc the engine only needs to overcome the drag of the sponsons and the thrust required to move it to whatever speed it can reach.

GT (still learning lots)

 

[Slideblues]

What I did was modify a existing design for SAW, and went extreme lite,

A better way would have been what Tommy just stated.

Tim,

No, the center section in the pic is different, it still has the offset and 6 1/4" width.

Its gonna be a test mule.

James your center section and a set of WOF 30's are goin together in a friend of mines shop, he is rigging and runnin it this spring, I dont let my special parts get to far away,

Gene

 

[Jimmy Whitbeck]

J. Whitbeck-The difficulty with building a tunnel for big speeds is that you must design the boat around what it is going to weigh and how fast you are trying to go. I do not think ultra light weight is the way to go for s.a.w. speeds with a tunnel.

what i had was a boat built with rods info he gave me when he lived out this way. and was trying differnt things from what he told me and tried one built real light using 1/16" ply and ect the boat when fliped was gone. so now i stick to what rod told me that works and have not tried any thing differnt but do wan't to make it longer as now i got some cmb's to try.

Jimmy

 

[Geraghty]

Jimmy,

I moved to Wisconsin 11 years ago and some things have changed in those 11 years,mainly propeller applications for SAW boats.Fast SAW tunnel boats are not going to be using "X" props anymore to do it.

The 7.5 SAW boat Tommy set all the records with is a good example.I am here to tell you that boat weighs about the same as a '78 Buick.Dam that thing is heavy.I'm guessing at least 8 probably closer to 9 lbs and the boat ain't that big.If you are going to be launching that boat all day you had better eat your Wheaties for breakfast. :blink:

The props that were making the big mile per hour made the boat go through a real ugly stage from about 40 to maybe 50 mph.The boat looked like it was having a grand mall seizure.It was from sponson to sponson and all over the pond.

After 50 the boat settled right down and the faster the boat went the harder the boat was planted.

I don't think that boat has ever blown over.

That is why the same boat holds the D,E,& F tunnel SAW records.

If the boat was any lighter it never would have made it through that ugly stage.

 

[Jerry Dunlap]

Re: make it through that ugly stage

Jeez, I'll qualify for early Social Security next month and I'm not sure I've ever made it through "that ugly stage ."

JD

 

[Jimmy Whitbeck]

Jimmy,I moved to Wisconsin 11 years ago and some things have changed in those 11 years,mainly propeller applications for SAW boats.Fast SAW tunnel boats are not going to be using "X" props anymore to do it.

The 7.5 SAW boat Tommy set all the records with is a good example.I am here to tell you that boat weighs about the same as a '78 Buick.Dam that thing is heavy.I'm guessing at least 8 probably closer to 9 lbs and the boat ain't that big.If you are going to be launching that boat all day you had better eat your Wheaties for breakfast. :blink:

The props that were making the big mile per hour made the boat go through a real ugly stage from about 40 to maybe 50 mph.The boat looked like it was having a grand mall seizure.It was from sponson to sponson and all over the pond.

After 50 the boat settled right down and the faster the boat went the harder the boat was planted.

I don't think that boat has ever blown over.

That is why the same boat holds the D,E,& F tunnel SAW records.

If the boat was any lighter it never would have made it through that ugly stage.

So Rod do you have any more pointers for a better boat than what you gave me ifo about? and is it a good idea to put multi steps in the rid surface? as the one i been making don't yet. but I'm getting tired of building wood boats just to trash them?

So Rod or Tommy any help that you two might want shed more light on this would be welcomed!

 

[Tom v.d Brink]

well i have been following this interesting topic to and i have a few thoughts.

I looked at the pictures of rod's boats that had history and i found two things

one thing i noticed was that there is no raised sponsons along the part connecting the center to the sponsons. was this done for a special airflow reason or just to keep the top sponson surface low.

another thing was the cowl of the red/orangt boat. it has no rounded top making the top cord smaller. again a lift reduction plan or coincidence?

another interesting topic was the stumble blocks.

do you use these on saw boats as well because the turn isn't that important?

right another thing in design i wondered was what is the effect of the tunnel length vs tunnel width? did you guys test this or should i also include tunnel height.

if so are there any known factors?

I've heard the 1/8 roundnoses try to keep as much out from under the tunnel by using a metal strip if necesarry. with the O/B weight point being even further back is this even worse for these boats. i do think the moutning of stumble blocks will help this some right?

well that's a start of thoughts i had in reading the past topics

It is always good to learn.

Tom

 

[Chris Wittrig]

Jimmy,I moved to Wisconsin 11 years ago and some things have changed in those 11 years,mainly propeller applications for SAW boats.Fast SAW tunnel boats are not going to be using "X" props anymore to do it.

The 7.5 SAW boat Tommy set all the records with is a good example.I am here to tell you that boat weighs about the same as a '78 Buick.Dam that thing is heavy.I'm guessing at least 8 probably closer to 9 lbs and the boat ain't that big.If you are going to be launching that boat all day you had better eat your Wheaties for breakfast. :blink:

The props that were making the big mile per hour made the boat go through a real ugly stage from about 40 to maybe 50 mph.The boat looked like it was having a grand mall seizure.It was from sponson to sponson and all over the pond.

After 50 the boat settled right down and the faster the boat went the harder the boat was planted.

I don't think that boat has ever blown over.

That is why the same boat holds the D,E,& F tunnel SAW records.

If the boat was any lighter it never would have made it through that ugly stage.

Rod hits the prop requirements and charcteristics dead on. Our setup that went 75 one way and ultimately 72 for a two way average looked just as he describes. The transition is the most critical part of the run and, consequently, the reason why many passes either fail entirely, or just plain aren't good. In that 40-50 mph range you are more a guy on the shoreline professing to have control of a boat that really just has a mind of its own. Getting the boat past that transition is the first challenge and once there you hope you were left with a reasonable alignment for the pass. Yep, X series props weren't on our list either.

 

[shoboat]

Chris,

I bet you guys used 1455 didn't ya? The RIGHT propeller diameter is the

KEY to this equation,plus the cup to pull her through the traps. Just think diameter,

the pitch or cup will be determined by the engine and the setup.

Thanks Chris,

Mark Sholund

Props-4-U

[email protected]

 

[GTR]

Doesn't pitch move you further forward (faster) per revolution more than diameter? So wouldn't a 1650 pitched up maybe be better than extra diameter?

GT :blink: