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Any Onslow 33s with twin 300HP power?

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Any Onslow 33s with twin 300HP power?

Old 01-18-2021, 12:40 PM
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Default Any Onslow 33s with twin 300HP power?

Working on my Onslow 33 build list and agonizing over power. Have had some informative PMs that say 2x 350 verados will give a max speed of low-mid 60s light and decent cruise economy at 40mph with a load. This would be perfect for me.

However, I have a slight aversion to non-Yamaha due to service availability and even more concern over supercharged engines. Not a yami fan boy by any means but the F300 is about as rock solid as it comes. Problem is I expect 2x F300 will not be sufficient power. And I do not want trips.

Onslow says 2x Verado 300 (V8s assumed) will give 60 light, 55 mph loaded, which seems a little optimistic to me given what multiple owners have said about 2x 350 verados (above).... and I expect the F300s to have a little less power than the 300 verados (since they deff have less efficiency at high engine speeds compared to the V8 verado, if you believe perf sheets).

So any input on twin 300 power, especially F300 power on a Onslow 33 would be most appreciated.
Old 01-18-2021, 12:49 PM
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Not on an Onslow Bay, but on an Intrepid 327 there was very little performance different between the Verado 350's and the Yamaha 300's, and the Yamaha had a slight advantage over the Verado 300. I spoke with a guy that had some of the first Verado V8 300's on a 327 and his performance sounded similar to the other motors mentioned. Bottom line, on an Intrepid 327 I did not see much difference, but every hull works differently.
Old 01-18-2021, 12:58 PM
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The 350 Verado and the 300 v8 Verado produce very close to the same power on 87/89 fuel
Old 01-18-2021, 01:16 PM
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That's a tough call, OB does not do many Yamaha powered boats. Not sure I would expect much of a speed differential Yamaha to Merc at 300hp.

I didn't want trips on my OB, til I drove his demo boat! My speed tends to remain close to RPM/100, and I wanted power for canyon loads thus triple V350's. I never looked back.
Old 01-18-2021, 01:20 PM
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I ran hull number 1 or 2 with twin 350 verados. The hull ran plenty fast but by memory wasn’t as efficient as I thought it should be compared to the 32st I think twin 300 Yamahas would be fine if you are going to be happy with a 55-58 mph boat.

Last edited by Knot Tight; 01-18-2021 at 02:00 PM.
Old 01-18-2021, 01:37 PM
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Get with Kevin Sneed at rigged and ready. He just repowered his 33 from twin 350 vrods to twin v8 300 last week. He should be able to give you a real good comparison.
Old 01-19-2021, 07:45 AM
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Originally Posted by KingRanch View Post
Get with Kevin Sneed at rigged and ready. He just repowered his 33 from twin 350 vrods to twin v8 300 last week. He should be able to give you a real good comparison.
Thank you very much for this. Spoke to Kevin, nice guy. He saw 58 max when light with 2x V350s (a little slower than others have reported) and 48 max full of gas, 4 ppl. With 2x V300s (in economy mode, whatever that is) he saw 52 max with 2 ppl and 2/3 full of gas. Or at least that's what my notes from the call say.

I think w/ any of the #s, +/- 3mph is a reasonable tolerance given the variables of current, wind, octane, phase of the moon, etc.

I want a solid 60mph boat. So for me, if I go F300, trips it is. If I go merc (eeeeewwwww), trip V8300 (AMS only since CMS does not come in a 30" shaft, good one merc marketing dept).

Thanks all.

Old 02-03-2021, 04:42 PM
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Originally Posted by NEBassMan View Post
Thank you very much for this. Spoke to Kevin, nice guy. He saw 58 max when light with 2x V350s (a little slower than others have reported) and 48 max full of gas, 4 ppl. With 2x V300s (in economy mode, whatever that is) he saw 52 max with 2 ppl and 2/3 full of gas. Or at least that's what my notes from the call say.

I think w/ any of the #s, +/- 3mph is a reasonable tolerance given the variables of current, wind, octane, phase of the moon, etc.

I want a solid 60mph boat. So for me, if I go F300, trips it is. If I go merc (eeeeewwwww), trip V8300 (AMS only since CMS does not come in a 30" shaft, good one merc marketing dept).

Thanks all.
I know there is a 33 that runs around here (docked in Spooners Creek in MHC) with twin F300 power. My 27 with twin F300s is a perfect pair IMO. The day I move up to a 33, it would be a trip F300 or twin F425 rigged.

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