CF 3.5 Rigger Project

[Twin_k90]

Mark,

Get a H7 and a H10, the H10 is 3.0" pitch, it is a big prop but if you have the power you will be screaming!!

Dale

 

[Mark Sholund]

Mike,

Just send a 1445 prop to Andy Brown at Competition Marine

Designs and have him pitch it to 3.1".He is a great prop guy

and I know they work.I run even more pitch but you have to

start at 3.1".Like I said before I can make you really fast but

you have to be patient.The altitude you run at is important

also.

Thanks,

Mark Sholund

Dale,

I don't care for an H-10 @ 3.0 my props are all the way up

and over 4.0" I go really fast.I have had 21 riggers for 14

years and I know a lot about props for any boat.

Thanks For The Help,

Mark Sholund

 

[Twin_k90]

If you care to pay someone heaps of money to do a prop then thats your choice, but i refuse to pay someone money when you can buy a prop and with a little work will work just as well if not better,

ive seen andys props and there nice, but until one of them beats me in heat racing ill continue to use out of the packet props and pitch them myself with my anvil and save a lot of money.

The quickets 21 rigger i have seen had a novarossi and a h7 on the back....

 

[TimD]

Lets not get into any arguments here - all we are trying to do is help out someone who is looking for advice.

"horses for courses" guys! ;D ;D

The MAC 21 GENERALLY works better with a smaller prop pulling very high RPM compared to say a Novarossi or a L/S CMB that produces a lot of torque (for a 21 that is) and operate at a lower RPM.

I'm with MikeP, I'd rather learn how to do something myself rather than rely on others - but I can also see Mark's point by buying a known worked prop (he is using the same motor too!). Something to keep in mind is that by bending your own props you are likely to ruin a few in the learning process.

Just my 2 cents worth.

 

[Twin_k90]

Wreaking a 21 prop is no where near as pricy as twin props!! now with the pitch guages kingcraft are selling we will be able to keep track of everything!!

 

[MikeP]

Ok, Here is the plan.

Order one from Andy and see what it's all about then start working on my own.

Mike

 

[Mark Sholund]

Mike,

Did you get your prop yet from Andy? I would need to

show you in person how to cup the props. So if you are

ever in MI give me a buzz.

Thanks,

Mark

 

[mike k]

Just wanted to add... NICE ! Wish I had those skills!

Are your rear sponsons flat at the rear? & what angle of attack ? What is your rear sponson setup?

Thanks

Mike

 

[MikeP]

Mark,

No prop yet. I should have it for next weekend. I have a friend that has one of Andys 1667 cupped 5 something I can compare with, that might give me an idea where the work is done.

Mike,

The rear sponsons are flat on the bottoms, the angle of attack is 3deg. I started with the front and rear height the same(not good) then lowered the rear 1/8" by cutting them off much better. lowered the rear another 1/16" better in the turns. Still going to do more testing. They are attached with double stick tape so I can play around with them. I am as fast as others here but I know they slow me down because I have run with them off. I am going to keep cutting them down until I go too far.

You can do whatever you want if you want it bad enough.

Mike

 

[MikeP]

Tried a couple of things this weekend, Set up a J&D with remote mixture carb. I ran side by side with a MAC and a stock carb. I noticed a different sound and the rpm's were highter. I could mill at half speed. It did consume alot of fuel and when it was on the pipe at speed small mixture adjustments didn't have much effect. It was nice to have the low end needle with the OS 4E but the J&D is a better carb for heat racing.

I took off the rear sponsons and the boat was much faster and handled the corners better(turned tight with less rudder input). I could not get it to launch, out of 8 tries got it up twice.

Any launching tricks that are reliable?

Need to reduce rear sponson drag and still launch 100%.

-MikeP

 

[Mark Sholund]

Mike,

What prop were you using?The 1445 from Andy is going to

be pitched or cupped on the tips of the prop.You need to

get some prop pliers from Tidewater so you can start bend-

ing your own props.The launching should be effortless,you

should not have to throw your arm out on launch.I just

drop mine in off the dock and it takes right off.You must

need to work on the rear of the boat more.Your pipe isn't

too short is it ? Why the different carbs on the MAC 21?

Mine runs STOUT with no work on it at all.We love the carbs.

Well I Need To Go,

Good Luck Mike,

Mark Sholund

 

[MikeP]

Mark,

I was just playing around and decided to take off the rear sponsons. Thats the only time I had problems launching. I noticed that I was alot faster without rear sponsons. How ever the pipe coould be a little short. Still running the stock 1445. Still waiting for new prop.

-MikeP

 

[Hammerhead]

Hey Mike! When you took off the rear sponsons, how was the cornering. If you slowed way down, and tried to speed up again, what happened? I have been thinking about building one with out rear sponsons. I'm very interested in the running characteristics. Never had the courage to try myself.

Thanks, Hammer

 

[MikeP]

Hammer,

I only got about 4-5 lap's in but I it was enough to see that the rear sponsons were slowing me down. It didn't slow me down in the turns without them, I think I was faster. In the turns I noticed that I needed about 1/3 less throw to turn, the rear was real responsive to the rudder. I do not know what will happen in rough water yet.

-MikeP

 

[Twin_k90]

When we were running the wood twin we tryed rear sponsons like the centre sponson on the eagle sg, it really messed up the turning and made it hop in the straight, pulled them off and instantly the turning was 100% better and no more hop and heaps more speed,

so now we dont run rear sponsons on any of the riggers

 

[MikeP]

Happy medium has been found.

Too many unpredictable problems came up running without rear sponsons. Got in some good runs without them and found that as the hull jumps there is no stability in the rear and the front sponsons would dance all over, cought a edge in the corner and did 2 or 3 cartwheels, it was also very twitchy in the straights.

I cut down the rear sponsons another 1/8"( not too much left now) and got them well off the water at speed. It's now what I would call in the sweet spot. Very stable and really fast, launches easy.

Time to try the 1445 pitched 3.1. Wow !!! I thought it was fast before, handles better, smoother in the straights and corners, it's hooked up.

-MikeP

 

[Hammerhead]

Hey Mike! Anyway to get a URL of vid of it running posted. I'm sure a lot of people would really like to see it.

Hammer

 

[Mark Sholund]

Mike,

So what do you think of Andy's prop? The 1445 is the Prop

for a 21 rigger I think.The boat will probably pull even more

prop what do you think?I was running the other day and we

were pulling around 3.2" to 3.7" cup on our 21 boats.Our

Speeds were 62 MPH to 72 MPH not bad with 95% A/D air.

I am happy the boat is running well for you now.In the

future save some money and send Andy a 1445 prop of

your own.He will also repitch the props for I think $9.00.

If you have the cash I would have Andy pitch a few more

for you,this way you will be able to test lap times also.

Talk To You Later,

Mark Sholund

 

[MikeP]

Mark,

Andys props are nice that's for sure, they are worth the wait and money. I thought I did a pretty good job on stock props. I see I can do alot more. I made an impression of the Andys blade with some sculpting clay and compared it to the stock 1445 to see where the modification is.

Do you think 3.4 " is too big of next step? With 3.1 everything has to be right or it does't pull it. I have had to go back to stock 1445 tune it up to speed then I can easily run the 3.1"

-Mike

 

[Mark Sholund]

Mike,

3.4" is too much for you right now but you will work into it.

Have you modified the motor yet? What did you find out

about the other carbs.?Did you go back to the stock carb.?

3.2" is the next step on your boat.What do you mean you

had to tune up your boat to pull 3.1"?It should pull that

easy.How do you tune up your boat?

I just run RICH and throw on the next bigger prop.I may

have to lean it a little to get Maximum Speed out of that

certain prop,but that is it.

thanks,

Mark Sholund