Expresscraft Thunderbolt Twin RCMK Build
WOW.......... 
08-08-2010, 10:53 PM
#7
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RE: Expresscraft Thunderbolt Twin RCMK Build
Ok...I've thought about it. I've googled it. I've even meditated on it. How do you create a counter-rotating prop system in a gas/nitro set up with out a gear box?
Forgive my ignorance,
Dan
Forgive my ignorance,
Dan
08-08-2010, 11:14 PM
#8
RE: Expresscraft Thunderbolt Twin RCMK Build
ORIGINAL: ddavis510
Ok...I've thought about it. I've googled it. I've even meditated on it. How do you create a counter-rotating prop system in a gas/nitro set up with out a gear box?
Forgive my ignorance,
Dan
Ok...I've thought about it. I've googled it. I've even meditated on it. How do you create a counter-rotating prop system in a gas/nitro set up with out a gear box?
Forgive my ignorance,
Dan
08-09-2010, 02:00 AM
#10
RE: Expresscraft Thunderbolt Twin RCMK Build
(Sorry to be going off topic on you here Gone in 60)
None that I have ever heard of with the Zenoahs and I am sure same can be said of all other full crank motors. Motors without a full crank (Homelites, Ryobis, McColloughs) do not have this option.
In fact this has been done with inline zenoahs for several years with no issues relating to performance or longevity coming from the drive option. [link=http://www.imageevent.com/justaddwata/myboats/geicocat?p=31&n=1&m=-1&c=2&l=0&w=4&s=0&z=4]The inline motor on the left in this pic[/link] had the output being taken from whats normally the pull start end of the motor where the one on the right is from the other.
ORIGINAL: ddavis510
Thanks. Do you see any lose in performance or longevity by hooking up to the other side of the crank shaft?
Thanks. Do you see any lose in performance or longevity by hooking up to the other side of the crank shaft?
In fact this has been done with inline zenoahs for several years with no issues relating to performance or longevity coming from the drive option. [link=http://www.imageevent.com/justaddwata/myboats/geicocat?p=31&n=1&m=-1&c=2&l=0&w=4&s=0&z=4]The inline motor on the left in this pic[/link] had the output being taken from whats normally the pull start end of the motor where the one on the right is from the other.
08-09-2010, 09:36 AM
#12
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RE: Expresscraft Thunderbolt Twin RCMK Build
Your the first person I've seen to put 2 motors in the Ex.-Thunderbolt. [X(] How's the hatch gonna fit? I guess I should wait til your finish building her..LOL... Love the looks of these hulls.
08-09-2010, 10:33 PM
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RE: Expresscraft Thunderbolt Twin RCMK Build
just out of curiosity did you have the boat shipped with the stringers for the motors already installed or did you install them? also what is the spacing between them? i havnt seen a set of motors mounted that way before, looks very clean. congrats, it looks beautiful
i just took a closer look at the pics, they came uninstalled. what does the spacing end up being?
i just took a closer look at the pics, they came uninstalled. what does the spacing end up being?
08-10-2010, 04:13 AM
#15
RE: Expresscraft Thunderbolt Twin RCMK Build
The above question is actually something I wondered about .......... by mounting engines the way you show you end up with 4 rubber mounts ... I did that 2 times before and hadseveral of mounts break the rubber isolators
I switched to a billet top mounts very simple to pull twins and I went to a thin center stringer ......... built 4 twins this way and have never broke a mount ... you lose one mount and I can see issues
I switched to a billet top mounts very simple to pull twins and I went to a thin center stringer ......... built 4 twins this way and have never broke a mount ... you lose one mount and I can see issues
08-10-2010, 01:36 PM
#16
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RE: Expresscraft Thunderbolt Twin RCMK Build
I had done a set of Modified counter rotated S254 Evos for another boater in southern Florida . If my memory is right his too were going into a big cat 
Word was ... holly fast cat !!
Scott
Word was ... holly fast cat !!
Scott
08-10-2010, 04:30 PM
#19
RE: Expresscraft Thunderbolt Twin RCMK Build
Your mounts might be fine ......... just thought I would meantion it ...
I'll look for some pics I did one wheren I built a twin where they shared a center rubber issolator rubber ...... I drilled large hole in center stringer (same size same ODof rubber) and the center rubber 'floated' in the stringer
That combination should be a real 'pocket rocket' ...................
Cheers
I'll look for some pics I did one wheren I built a twin where they shared a center rubber issolator rubber ...... I drilled large hole in center stringer (same size same ODof rubber) and the center rubber 'floated' in the stringer
That combination should be a real 'pocket rocket' ...................
Cheers
08-10-2010, 06:00 PM
#21
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RE: Expresscraft Thunderbolt Twin RCMK Build
60 +/- will take some tuning, right props with correct pipe settings.
70+
.... Don't hold your breath.
This nothing more than an opinion [:'(]
70+
.... Don't hold your breath.This nothing more than an opinion [:'(]
08-10-2010, 06:16 PM
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RE: Expresscraft Thunderbolt Twin RCMK Build
Had mine up to 65-66 with a QD HT. Motor had more but couldn't keep it on the water, even with 1lb of lead up front. Your CG will be higher than mine (32%-33%) with 2 motors up front. Try to shoot for 35% and who knows?? My guess would be what I was able to hit in mph. QDHT spins hard and mine weighed less than what your going to finish with, but I could be wrong. I know that some of the guy's in salt water with a QD were knocking on 70. You could be the 1st to hit or exceed 70mph with a Ex-T Bolt which would be cool. Best of luck and can appreciate someone who is thinking outside of the box. [sm=thumbs_up.gif]
08-10-2010, 06:23 PM
#23
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RE: Expresscraft Thunderbolt Twin RCMK Build
Nice project! It is fun seeing the first (that I know about) side-by-sinde twin in a EXP Thunderbolt!!! I have seen a skater (and was surprised it fit in THERE). I have always loved the lines of the Thunderbolt. seen a twin Side-X in a EXP MTI cat and didn't think it could be done well...I LIKE IT!
Look closely at the transom on this hull. A firend had one and spent some extra time making sure the transom was square when it came time for final setup just prior to paint. It didn't take long but MUCH easier completed prior to paint for obvious reasons.
Keep the updates coming!
Look closely at the transom on this hull. A firend had one and spent some extra time making sure the transom was square when it came time for final setup just prior to paint. It didn't take long but MUCH easier completed prior to paint for obvious reasons.
Keep the updates coming!
08-10-2010, 07:19 PM
#24
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RE: Expresscraft Thunderbolt Twin RCMK Build
ORIGINAL: gtopillado
Had mine up to 65-66 with a QD HT. Motor had more but couldn't keep it on the water, even with 1lb of lead up front. Your CG will be higher than mine (32%-33%) with 2 motors up front. Try to shoot for 35% and who knows?? My guess would be what I was able to hit in mph. QDHT spins hard and mine weighed less than what your going to finish with, but I could be wrong. I know that some of the guy's in salt water with a QD were knocking on 70. You could be the 1st to hit or exceed 70mph with a Ex-T Bolt which would be cool. Best of luck and can appreciate someone who is thinking outside of the box. [sm=thumbs_up.gif]
Had mine up to 65-66 with a QD HT. Motor had more but couldn't keep it on the water, even with 1lb of lead up front. Your CG will be higher than mine (32%-33%) with 2 motors up front. Try to shoot for 35% and who knows?? My guess would be what I was able to hit in mph. QDHT spins hard and mine weighed less than what your going to finish with, but I could be wrong. I know that some of the guy's in salt water with a QD were knocking on 70. You could be the 1st to hit or exceed 70mph with a Ex-T Bolt which would be cool. Best of luck and can appreciate someone who is thinking outside of the box. [sm=thumbs_up.gif]
Now add another 6-7 pounds with another engine/mount/pipe/drive parts etc, boats overall weight just went up over 30% or more !!
The added weight very well may keep it from blowing off but will also effect the top speed due to running wetter.
**Gas Twins have a serious WOW factor, but yet to see a twin gas run equal too or exceed a single used apples too apples in equal hulls.
Again, just keeping it real and in perspective.
08-10-2010, 07:35 PM
#25
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RE: Expresscraft Thunderbolt Twin RCMK Build
I'd have to agree, I really don;t think you'll see 70. I'm not sure the hull would take 70. But we'll see. I'm kind of in the same boat doing twin side by sides in an MTI. I'd love to have 70 but would be tickled with 65 and running well.
Neat project. Other than Tom at Excraft, your the first that's done it, I think.
Hope you reinforce the hull. My T-bolt subbed at 50 mph and folded up. It was a very light layup.
Thanks for sharing your project.
Neat project. Other than Tom at Excraft, your the first that's done it, I think.
Hope you reinforce the hull. My T-bolt subbed at 50 mph and folded up. It was a very light layup.
Thanks for sharing your project.