Another, Even Flatter Thing!

Nice bit of footage......what about rpm's and top speed?

Helmsman seemed a happy bloke :)

There's no doubt that video footage really takes you to the place though!
 
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Wow James,
looks like a smooth ride indeed!
Surprised to see such a narrow channel with no speed limit.
Or did you miss it maybe? :D
 
I would if I knew how to do it, trouble shooting engine diagnostics no problem, but email, media and mobile phones, my missus knows more than me!
 
51/52 knts (gps) at around 5000rpm, on a 26" pitch prop set, I think it is the same motor as that in Mapis M's Fountain, the Cobalt is probably much heavier and the drive a duoprop B3 helps with grip but has much more drag than the racing single prop B1 drive.
 
No speed limit Mapis M in the Straits at this location, we have just left behind a speed limit at Port Dinorwic as the video starts and are entering another as the video ends at Caernarfon. The area in the video is tidal, there are huge areas of shallow sandbanks either side of a marked channel we are in.
 
Come on Spannerman, take the wife out and show us what 100knts is like on a Fjord in a big Nor-Tech cat with the blue top motors screaming?
 
JamesTT said:
I think it is the same motor as that in Mapis M's Fountain, the Cobalt is probably much heavier and the drive a duoprop B3 helps with grip but has much more drag than the racing single prop B1 drive.
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All correct JTT, though I wouldn't really call the B1 a racing drive, even in its stronger XR version.
And aside from semantic, there are other differences, which are also relevant.
Your B3 has a reduction ratio of 1.81 (my guess, but a pretty safe one, based on your figures), against the 1.5 of my B1. And your leg is surely installed with a standard X dimension, i.e. with the cavitation plate aligned with the hull bottom. My leg is much higher, thus reducing drag further and working almost as a surface prop (hence the sort of semi-rooster tail visible in my clip).
For these reasons, it's easy to guess that your boat, albeit heavier, would outperform mine easily in holeshot acceleration.
And 52 kts is an impressive speed anyway. Cobalt hulls definitely deserve their excellent reputation!
 
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JamesTT said:
No speed limit Mapis M in the Straits at this location, we have just left behind a speed limit at Port Dinorwic as the video starts and are entering another as the video ends at Caernarfon. The area in the video is tidal, there are huge areas of shallow sandbanks either side of a marked channel we are in.
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Now you tell me!!!! I wish I had known about them sandbanks 2 weeks ago when we found ourselves in 18 inches (yes, you read it correctly) of water with four adults on board about a mile out of Caernarfon. Oh the joy of having a small boat (compared to many on here) & a bit of momentum. As one well known forumite pointed out on our return to Dinorwic 'At least you gave your prop a good sand-blasting.' He was right, when I checked said prop, it had not a blemish on it &, thankfully, was still in shape. Lesson learned!
 
More sand than water Lawsy. After my first outing to Caernarfon many years ago I grounded, but wasn't so lucky. I took what was left of my prop in for repair and the guy at the desk held it in his hand and said "what is it?"
 
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