The pros and cons of repowering above the manufacturing max

[Ranchero50]

I don't see anything that's open to the imagination or open to interpretation in the CFR 33-183 series. I think that's where we have a fundamental difference of viewpoint. I've spent the last year trying to wade through Maryland's new gun laws so I've learned to read the law as written and not to try and interpret it.

That the USGC standard has been standard since 1971 says a lot about the basic tests that a hull needs to pass to get a higher HP restriction.

With reference to your first post, if you would have just linked the law and discussed it I don't think there would be much controversy. Instead you post a wall of text that rambles and does not back up the title of this thread with facts. Facts minimize confusion. This thread has been confusing from the start.

Even the sentence from the original post that you highlighted in your misquoted reply to me has items in it that are not conditions for determining the max HP for a given size and type hull per the CFR 33-183 law. Fortunately Sumdumguy found the link and posted it up to help clear up your confusing layers of posts.

Reread this and think about what you are insinuating vs. what is the truth per the law;

'There is a formula that is somewhat standard but it leaves much to the imagination and is open for interpretation. Length, with, transom thickness and height along with the hull materials all factor in. The one thing that is crystal clear is they are always going to error on the side of caution.'

The formula is very standard for under 20' outboard powered hulls. Length and width matter. Transom thickness or height have no bearing, nor does hull material (that I could find). The only thing that seems to matter is if it's a sub 13 foot racing hull, a flat bottom / hard chine hull or has remote steer. You don't mention the 35mph running speed condition which is the largest factor in rating higher HP (speed) hulls nor the quick turn and avoidance course safety checks which per the law are why the manufacturer leans on the side of caution.

Fundamentally an over powered hull isn't going to perform a 90` full lock turn at wide open throttle in a lighter weight hull in a stable manner. Fundamentally the same may apply to the avoidance maneuver.

So, legally unless the hull can perform both those functions above 35 mph it is unsafe and will be derated to an engine HP where it can perform those functions in a safe and stable manner.

 

[Ranchero50]

JMichael » 11 minutes ago[/url]"]Well I guess I'm just slow because I'm still not sure how they calculate the hp. In their explanation,

Compute a factor by multiplying the boat length in feet by the maximum transom width in feet excluding handles and other similar fittings, attachments, and extensions.

does this mean the widest point of the transom, as in the top of the transom and not the width at the base? If it does, that might explain how your 1436 is rated higher than a 5hp.

Yeah, I think that's the way they are doing it as it would relate to the widest part of the hull being at the top for modern small boats. Run the numbers and see if makes more sense. My math and reading comprehension sucks... :?

 

[Jim]

Alrighty then. Everyone has stated their opinion and facts. Let's move on from this thread please.

 

[Country Dave]

Ranchero50 » 02 Nov 2013, 18:31[/url]"]C/D, your formula doesn't compute for 90% of the members of this forum who own smaller hulls.

Mine: 14' x 4' = 56 - 90 = -34 hp Does -34 hp mean I can only paddle?

Please post up the sources for your information because honestly it doesn't pass the smell test and as said above is just going to confuse someone into an unsound situation.

Quick Google search for boat data plates brings up these guys who do replacement decals;

https://garzonstudio.com/boat/capacity-decal.html

Please note that each plate says the same thing about complying with the USCG ratings for HP and load.

I know it’s absolutely going to kill you if you don’t get the last words but I’ll play along.

Firstly that’s quite a pompous stamen for someone who didn’t know anything about the “the Federal Boating Safety Act of 1971 (FBSA)” until I posted about it. Then you couldn’t grasp the simple and clear mathematical equation of the baseline formula “I even gave a very clear example” so you questioned its validity and now you’re quoting it like you penned it. Talk about irony. LOL

Sorry you’re so confused. Here are some facts for you. The formula provided in the regulations reduces to (2 X L X W) -90 = rated horsepower L=boat length W=transom width; if the boat does not have a full transom, the transom width is the broadest beam in the aftermost quarter length of the boat. The rated horsepower may be rounded up to the nearest "5".
This is the baseline or starting point and yes they are other factors some of with I mentioned and some that I did not because I was not aware of them at the time. Somebody found them “Not you”

This was a search for how a boat manufacture goes about detraining a max HP rating for a hull. The FBSA outlines a standard for the manufacture however they are free to put a lower HP rating on their hull if they so desire, and that was my whole point. You obviously missed that along with much else.

The other factor I mentioned in my original post was directly from phone conversations I had with different manufactures when I was repowering one of my boats. Just as they are free to lower the HP they are free to take into consideration hull material etc. I’m all about trying to give back to this great forum and admittedly I’m not an expert on max HP rating but all in all I think it was a good post. We just need to get away from the personnel attacks when you don’t agree with someone’s opinion.