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FE faces some interesting challenges.


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#46 Terry Keeley

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Posted 03 October 2018 - 08:15 AM

As a nitro guy this doesn't affect me personally, but as CD of the Can-Am and two FAST record trials per year I was amazed when I discovered this fact.

 

If this rule set transferred to nitro I could run twin 45's in a "single" 45 class (IMPBA D hydro).  Or twin 67's in the single 67 class (IMPBA E hydro).  My hulls wouldn't necessarily be any faster but they would accelerate much quicker and could be 1/3 bigger to handle race water better which would be a clear advantage. 

 

Our F hydro class has a wide displacement range so that's where we get twins and singles running together, but if someone made a 30cc nitro motor it would compete well against twin 15cc power plants.

 

Don't seem right to me but I don't have a solution for you guys, sorry... :mellow:  




Edited by Terry Keeley, 03 October 2018 - 09:45 AM.


#47 LohringMiller

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Posted 03 October 2018 - 09:17 AM

I would think that with equal total power the drag of two propeller shafts would make twins slower.  The advantage of a twin is eliminating torque and prop walk with counter rotating props.   Since those effects cause some additional drag, that could reduce the drag advantage of a single shaft.  Another effect is from prop diameter.  Since the total power of a twin is split between two props, they should have a smaller diameter than a prop on a single with the same total power.  That again should make the single's prp more efficient. 

 

As far as I know, all the fastest SAW records are held by single shaft boats.  Electric cats are very fast, however.  They can be built with stinger drives that are low drag.  Cat hulls probably won't be as fast as riggers of the same power, though.

 

Lohring Miller





#48 Terry Keeley

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Posted 03 October 2018 - 09:50 AM

I would think that with equal total power the drag of two propeller shafts would make twins slower.  The advantage of a twin is eliminating torque and prop walk with counter rotating props.   Since those effects cause some additional drag, that could reduce the drag advantage of a single shaft.  Another effect is from prop diameter.  Since the total power of a twin is split between two props, they should have a smaller diameter than a prop on a single with the same total power.  That again should make the single's prp more efficient. 

 

As far as I know, all the fastest SAW records are held by single shaft boats.  Electric cats are very fast, however.  They can be built with stinger drives that are low drag.  Cat hulls probably won't be as fast as riggers of the same power, though.

 

Lohring Miller

 

 

Pretty sure the IMPBA P, Q, S & T Catamaran SAW records are twins:

 

Pg. 6:   https://nebula.wsimg...0&alloworigin=1



#49 HTV Boats

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Posted 03 October 2018 - 10:51 AM

IMPBA allows twins in Q and above. NAMBA allows twins in P and above.

 

The IMPBA cat SAW records respectively are:

P-78.508 mph  (NAMBA P record w twins - 102.881 mph)

Q- 112.163

S- 128.278

T-119.836

 

The Mono records are:

P-79.730

Q-77.293

S-79.874

T-91.974

Hydros, Sport Hydros and Tunnels and similar in differences to Mono records

 

Mic


Edited by HTV Boats, 03 October 2018 - 05:25 PM.


#50 RaceMechaniX

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Posted 03 October 2018 - 06:17 PM

I say with high confidence most SAW boats are unique compared to their oval brethren and don't cross over well.  It is true all the SAW records for CAT's are held with twin set-ups possibly with one exception in the single cell class.  This includes US rules and European rules where twins are allowed even in the single cell classes.  I just returned from the Munich SAW event where racers are truly pushing the limits.  I watched a 4 cell non-paralleled twin motor cat run 109mph.  I watched an 8 cell non-paralleled cat run 142mph.  And of course Joerg M just ran over 200mph with a 8 cell hydro!

 

Want a good laugh, watch any SAW boat try to turn at oval racing speeds.  They just flip and role.  


Edited by RaceMechaniX, 03 October 2018 - 06:17 PM.


#51 LohringMiller

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Posted 04 October 2018 - 09:23 AM

IMPBA allows twins in Q and above. NAMBA allows twins in P and above.

 

The IMPBA cat SAW records respectively are:

P-78.508 mph  (NAMBA P record w twins - 102.881 mph)

Q- 112.163

S- 128.278

T-119.836

 

The Mono records are:

P-79.730

Q-77.293

S-79.874

T-91.974

Hydros, Sport Hydros and Tunnels and similar in differences to Mono records

 

Mic

And all the IMPBA hydro records are faster.  I believe they were all set with single prop setups.  Cats are a special case where twins are a natural.  Also the torque countering effects of an electric twin should help handling for two lap records.  However, outside of cats, are any two lap records held by twins?

 

Lohring Miller



#52 Jeffmaturo

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Posted 04 October 2018 - 12:03 PM

I think just by talking about this we are heading in the right direction. Doesn't sound like it will happen over night but I think brought to a vote we can tell exactly what a majority of members want. Either way, I will support the decision and move forward. Lohring, I honestly don't know about that but as you have said, twins do have an advantage. 



#53 T.S.Davis

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Posted 19 October 2018 - 11:51 AM

The spec classes still have the best dollar to giggles ratio of all of our classes in my opinion.   They were never intended to be a beginner class.  The intent was for it to be a place for everyone that wasn't necessarily dominated by someone's wallet.  A class for the new guy and the veteran to coexist in pieceful harmony.  (picture me typing with butterflies flitting about)

 

If you look at Mike's IMPBA recommendation for 4s spec motors you'll find very little hand wringing over it.  With the exception of the weight.  It may need to be shaved a tic.  260 grams maybe vs 265 grams?  We've raced the crap out of this for a couple seasons now.  Ran all kinds of variants too.  From the most expensive to the least.  Middle of the road cost motors are still the best option we've seen so far.  My brat kid killed everyone this season with the relatively inexpensive Proboat motor option in spec sport.  My point is, you can't buy wins with the Mike's suggested guide.  Not so far at least.

 

I really think it could be a rule but getting the BOD to agree to it is a tall task.  Primarily because some have been such complete jack holes while we prove the concept.  The perception is that it's too controversial and no matter what someone will be crying.  I think this latest rendition that Mike has outlined is so close to correct that it should/could/would put it to rest for quite some time.

 

The twins thing you have to see to appreciate.  A single cat no matter who set it up is absolutely not in the same league as a well set up twin cat.  SAW or oval.  Sorry, it isn't.  Watched PAGS and Baffer run with Larry at the CanAm.  PAGS has won so many national championships in Q cat that he probably has more wins than anyone since LiPo were added to the rule book.  Baffers boat is a direct copy.  So two of the best cats in the country. Larry's twin boat will leave them for dead.  He's got multiple stable mph on them.  That's not to say Larry can put it on the pins but put that boat in the hands of someone that can and then what?  Hosed. 

 

I don't have a solve for that either but don't kid yerselves, a single and a twin Q cat have no business competing with each other.  As it sits today, if you're going to race Q cat in the north you better be building a twin.  PAGS is working on one right now.  One of our locals is too.

 

Not sure on the mono twins.  They don't work as well.  We saw a twin Q mono in Flint for the trial.  The problem appeared to be (to me at least) that the props lift the boat up and out of the water quite a bit.  So almost no keel in the water. Just the rudder.  Especially at 75mph+.  If a wisp of wind or a lateral wave tilts the boat even a few degrees you end up with one prop in the water and no keel in the water.  Shawn finally killed his boat this way.  Came off in the mid 70's



#54 Terry Keeley

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Posted 20 October 2018 - 02:44 PM

The spec classes still have the best dollar to giggles ratio of all of our classes in my opinion.   They were never intended to be a beginner class.  The intent was for it to be a place for everyone that wasn't necessarily dominated by someone's wallet.  A class for the new guy and the veteran to coexist in pieceful harmony.  (picture me typing with butterflies flitting about)

 

If you look at Mike's IMPBA recommendation for 4s spec motors you'll find very little hand wringing over it.  With the exception of the weight.  It may need to be shaved a tic.  260 grams maybe vs 265 grams?  We've raced the crap out of this for a couple seasons now.  Ran all kinds of variants too.  From the most expensive to the least.  Middle of the road cost motors are still the best option we've seen so far.  My brat kid killed everyone this season with the relatively inexpensive Proboat motor option in spec sport.  My point is, you can't buy wins with the Mike's suggested guide.  Not so far at least.

 

I really think it could be a rule but getting the BOD to agree to it is a tall task.  Primarily because some have been such complete jack holes while we prove the concept.  The perception is that it's too controversial and no matter what someone will be crying.  I think this latest rendition that Mike has outlined is so close to correct that it should/could/would put it to rest for quite some time.

 

The twins thing you have to see to appreciate.  A single cat no matter who set it up is absolutely not in the same league as a well set up twin cat.  SAW or oval.  Sorry, it isn't.  Watched PAGS and Baffer run with Larry at the CanAm.  PAGS has won so many national championships in Q cat that he probably has more wins than anyone since LiPo were added to the rule book.  Baffers boat is a direct copy.  So two of the best cats in the country. Larry's twin boat will leave them for dead.  He's got multiple stable mph on them.  That's not to say Larry can put it on the pins but put that boat in the hands of someone that can and then what?  Hosed. 

 

I don't have a solve for that either but don't kid yerselves, a single and a twin Q cat have no business competing with each other.  As it sits today, if you're going to race Q cat in the north you better be building a twin.  PAGS is working on one right now.  One of our locals is too.

 

Not sure on the mono twins.  They don't work as well.  We saw a twin Q mono in Flint for the trial.  The problem appeared to be (to me at least) that the props lift the boat up and out of the water quite a bit.  So almost no keel in the water. Just the rudder.  Especially at 75mph+.  If a wisp of wind or a lateral wave tilts the boat even a few degrees you end up with one prop in the water and no keel in the water.  Shawn finally killed his boat this way.  Came off in the mid 70's

 

 

Where's the like button?  :)



#55 Jeffmaturo

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Posted Yesterday, 02:45 PM

Terry,

 

That is exactly why I started this thread. This is one of several things that has to be looked at. The solution is simple, run twins separately. 



#56 RaceMechaniX

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Posted Yesterday, 04:42 PM

The spec classes still have the best dollar to giggles ratio of all of our classes in my opinion.   They were never intended to be a beginner class.  The intent was for it to be a place for everyone that wasn't necessarily dominated by someone's wallet.  A class for the new guy and the veteran to coexist in pieceful harmony.  (picture me typing with butterflies flitting about)

 

If you look at Mike's IMPBA recommendation for 4s spec motors you'll find very little hand wringing over it.  With the exception of the weight.  It may need to be shaved a tic.  260 grams maybe vs 265 grams?  We've raced the crap out of this for a couple seasons now.  Ran all kinds of variants too.  From the most expensive to the least.  Middle of the road cost motors are still the best option we've seen so far.  My brat kid killed everyone this season with the relatively inexpensive Proboat motor option in spec sport.  My point is, you can't buy wins with the Mike's suggested guide.  Not so far at least.

 

I really think it could be a rule but getting the BOD to agree to it is a tall task.  Primarily because some have been such complete jack holes while we prove the concept.  The perception is that it's too controversial and no matter what someone will be crying.  I think this latest rendition that Mike has outlined is so close to correct that it should/could/would put it to rest for quite some time.

 

The twins thing you have to see to appreciate.  A single cat no matter who set it up is absolutely not in the same league as a well set up twin cat.  SAW or oval.  Sorry, it isn't.  Watched PAGS and Baffer run with Larry at the CanAm.  PAGS has won so many national championships in Q cat that he probably has more wins than anyone since LiPo were added to the rule book.  Baffers boat is a direct copy.  So two of the best cats in the country. Larry's twin boat will leave them for dead.  He's got multiple stable mph on them.  That's not to say Larry can put it on the pins but put that boat in the hands of someone that can and then what?  Hosed. 

 

I don't have a solve for that either but don't kid yerselves, a single and a twin Q cat have no business competing with each other.  As it sits today, if you're going to race Q cat in the north you better be building a twin.  PAGS is working on one right now.  One of our locals is too.

 

Not sure on the mono twins.  They don't work as well.  We saw a twin Q mono in Flint for the trial.  The problem appeared to be (to me at least) that the props lift the boat up and out of the water quite a bit.  So almost no keel in the water. Just the rudder.  Especially at 75mph+.  If a wisp of wind or a lateral wave tilts the boat even a few degrees you end up with one prop in the water and no keel in the water.  Shawn finally killed his boat this way.  Came off in the mid 70's

 

At least in Q offshore a single mono is pretty damn competitive against a single or twin Q cat.  I lost a national championship by one buoy cut.