Fed requirement for USCG max capacity plate - Page 6

uncleboo · #51 03-29-2010, 09:30 AM

I'll get back to you. Mine is still legible, just looks like crap.

DonV · #52 03-29-2010, 10:23 AM

I'm still good for the 23', when you get to a dozen of the 23'ers let me know what I owe.

jongolds · #53 03-29-2010, 10:48 AM

Quote:

Let me be clear. The list has to be for identical decals, not total decals. The minimum run is 12 decals that are the same. So for 23's, there would have to be 12 decals ordered for 23's, or 12 for 20's, etcetera.

Looking at the specifications page, it looks like even among the 23s, there might be some differences, at least between the Sceptres/Tsunamis and the CCs. I don't want to be a wet blanket but I'm only interested if the information is going to be accurate for my model. Also, the formula doesn't seem to match the specs page. It lists 500hp for the 23 Sceptre but the formula would only yield 282hp. Am I doing this right, 23.25'*8'*2=372, 372-90 = 282?

Fr. Frank · #54 03-29-2010, 11:32 AM

The formula for multiple engines is different. I don't have the current (2005) publication.
My 1987 USCG home boat-builder's publication says the max rating is dependent on the height of your transom and length of your boat. For twin-OB vessels less than 20'0" in length with a transom of 20" or 15", the formula is the same as for a single motor. For twin-OB vessels less than 20'0" in length with a transom of 25" or greater, the multiplication factor is 2.5. So a 19'8" SeaCraft with a 25" transom and twin engines has a maximum hp formula that is (20X8X2.5)-90=310.

[b]For vessels over 20'1", there is no legal maximum horsepower, only "manufacturer's recommended maximum horsepower".

The USCG recommended using a test called the "quick-turn test" to determine the maximum safe horsepower limitation for home boat builders, where your maximum safe horsepower was whatever you could make a full-throttle turn with. The turn was accomplished by turning the steering wheel 180* at full speed with whatever prop you had installed. If you could do that without losing control, you were good. That's very subjective.

If I was using twin V6 Merc EFI's from 1997, with a maximum engine angle of 37.5* from center, and a SeaStar hydraulic steering system with 4.2 turns lock to lock, a 180* turn of the steering wheel will only turn the motor angle to 8 degrees from centered. While I wouldn't try turning like that with an Allison XTB at 105 mph, I would have no problem doing that with a 23' SeaCraft with twin 300 hp motors at full throttle and max trim.

So legal max OB horsepower for a 23 is pretty much whatever you want it to be. I would probably just stick the to old 500 hp max rating on the Potter built hulls.