Yamaha 300 on V21 performance

B

bgreene

Banned
Only weighs about 40lbs more than my 200 Etec HO, so why not.

Using the rough guide of 6-8 mph for every 50 hp increase, let's be conservative and figure 12 mph faster than the big block 200.

So, figure top end around 62 mph, with " easy cruising of 45-50 mph" all day long.

Just when you thought the " how fast posts " were done.
 
Ridges boat is already running those speeds with a 250xs, I'd expect a 300 sho to run in the upper 60's-low 70's if set up properly.
 
spareparts said:
Ridges boat is already running those speeds with a 250xs, I'd expect a 300 sho to run in the upper 60's-low 70's if set up properly.
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I suppose, but I believe Ridge is running with a bracket with engine high up........
Anyway, ok, upper 60's, sure why not. The boat would likely tend to get " squirrely" at times. I felt that once while fully trimmed out while running to confirm absolute top speed. It was starting to dance a little at around 50 mph, but then in the other direction was rock steady.

Let's rig one up and see how it runs. Now who's going to donate the new Yami 300 hp 4 stroke, rigging, and prop ?
 
spareparts said:
some one give me the $22,000 and I'll make my V run faster than that
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I'm thinkin a 280 MERC 2.5L would do the trick. Or you could find an old EVINRUDE V8 that's been worked a bit for well under $10K and say hello to 60+(if not put it well into the 70's). Then again somebody better be looking into building a pad in the back to be able to keep it straight at speed.
 
I agree, your gonna pass the hull speed with the v-8, guaranteed with Sr. Dave Bush hands on it. I always assumed "hull speed" to be the outer limit. So has anyone ever found that limit? Work on COG and a pad. Reduce the tendency to fly the nose while getting more of the boat dry. A 300 configured correctly I would think could put you near ridiculous speed. Did I mention a serious weight reduction of the hull and scantlins too? Composite everything and light. Made just for running. a Dave Bush v-6 would get you there. Check out the accelleration and sound on this bassboat. http://www.youtube.com/watch?v=1kKIiUQpk-Y or any Dave Bush video for that matter.:beer:http://www.youtube.com/watch?v=GcrpMbSXWF8
 
I'm just saying that the new, lighter Yami 300 could work on a V21.

Generalizing with 8-10 mph speed increase per 50 hp, I'm still thinking 65 mph top end.

This is with the standard transom, not the bracket.

Using the tabs and engine trim, calm water 50 mph " cruising speed " should be fairly easy.
 
E-tec powered STV Summerford Tunnel Vee - River Rocket with a shortened mid runs 127 mph on the Suwannee this past weekend.
Monty Racing. Literally dozens of HP boats. Here are a couple.. Suwannee Nov. 2013 018.jpg

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that Talon is the deal, always one of my favorites. The 'stream looks brand new, hope the coring has been replaced. trying to figure out the rest, black hulled boat Lake and Bay? orange tunnel Cobra? That's Seebolds old IOGP two seater? One year at Augusta, they took some girl that was a news caster for a spin in it. they had a hot mike on her. When Bill hit it from the dock, she screamed all the way to the first pin, after pulling 4 g's in the first turn, she fell silent. They only did one lap
 
Yes that is Parker Rabe with the inline 2 seat Seabold, giving a few uninitiated folks a ride. The Copper colored cat is a Simmons Custom Boats. The 22' twin rigged Talon has 200XS's. The black hull is a Big-O bass boat converted into a 84 mph flats boat. The Viper Hydrostream is like brand new, the seats are even original. This is the 1979 that never had the holes drilled in the transom until recent.

There was a 30+ footer full canopy offshore cat at the Santa Fe split when we got there. Lots of eye candy. Dozens of boats couldn't find a place to pull-up on the point. That means there were well over 100 boats. I had a rope on this one but let it get away.. Towing Shot.jpg This is when 250 hp comes in real handy.
 
I think the big o and the lake and bay are very similar. What was that on your line? Intimidator? Wasn't that Mragu's stream?
 
In tow is a 20' Superboat with a locked up 225 Merc. 23MPH at 4000 RPM anything more and the superboat would wash over the curl and surf on my wake making the occupants real nervous, myself included. Longer rope or bridal action would have been easier. Where is McGyver I mean Ferman when you need him?
 
Yami 300 on V21 with trim tabs, that would do it. Could adjust that just right and avoid porpoising too. Of course, how often is the ocean flat enough to run over 50 mph in a 20' boat ? Would have to run mostly calmer bays that have some size.........or the Del River.

Imagine cruising speed of 50 in one of these ? That's my boat's top, top speed with the bimini down and light. Trimmed for that speed, not a lot of boat in the water...or motor.
Add another 10 or 15 mph ? Might be just a tad squirrely !
 
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