Thread: Anyone ever break the rules when it comes to re-power the main engine?

Originally Posted by yobuck

Have you considered keeping the motor and changing the boat? lol

Not a chance, loving the Lund Alaskan thus far. It’s turned into a nice fishing boat, then coverts into a duck hunting boat in winter


Sent from my iPhone using Tapatalk

Originally Posted by wicklundrh

33 CFR 183 will provide all of the information regarding the Label.
Specifically, Sec. 183.53 will tell you everything you need to know about how HP capacity is calculated.

All of the above being said, there is a way to repower your boat (especially an older one) if you follow todays calculation requirements. If you do so, you can apply for a new ratings sticker. Below is a link to where you can find all of this information along with a place to purchase a new ratings plate or sticker.
Boat capacity sticker replicas | GarzonStudio.com

The reason this has come to light is that many boats (pre 4 stroke era) had previous HP designations that are now obsolete. This gives the user the ability to repower their boats with 4stroke motors. Keep in mind that, in some cases, the HP ratings actually go down.

With this being the case, one could then prove that a 135HO motor would be no different than a 150hp 4 stroke motor thus aquire the proper steps (with calculations) to obtain a new sticker.

I looked up the code 33CFR 183.53, determined the calculation for my boat - Length 21'6" x transom width 90" or 7.5' gives me a factor of 162, following the chart of remote steering and 25" transom (2x factor of 162) 324 minus 90 = 234 hp rounded to nearest multiple of 5 would be 235 hp. Would i apply for the new rating to the coast guard?

Thanks

Your rated for 125hp, and came up with 235hp???? WOW, that's quite a spread.

You have to remember however that, once you get the rating for what the boat can handle, testing must then be done to ensure it meets certain factors. The "Quick Turn Test" is what gets the HP ratings lowered.

(ii) For boats capable of 35 miles per hour or more, the maximum horsepower capacity must be the maximum horsepower with which the boat was able to successfully complete both the Quick Turn Test Procedure in Sec. 183.53(b)(4) and the Test Course Method in Sec. 183.53(b)(5) at full throttle.

So, the math is done and a maximum rating is given. Once that is complete, testing is done to ensure the above. In other words, just because a boat can handle straight line speed, the quick turn test is used to ensure "stupid people" are not using an overpowered boat to turn at full throttle!!!! I know, we have to pay for stupid people!

The only reason I know any of this is that my brother in law was an engineer at a boat company. After a boat protype was built, it would come down to his shop for testing. They would first install a safety cage at the helm to protect the driver (usually him). They would then go out and basically beat the ever living heck out of a boat. This included the "Quick Turn Test". If it could not perform as required, they would have to drop HP and perform the test again. Once complete, the boat would then be gone over with a fine tooth comb. They would mark all stress cracks, fractures, and so on so that it could then go back in and have additional supports, bracing, and anything else added. They would get a new prototype and start the testing again until it was correct.

Like mentioned, many boats can handle a much larger motor however, due to the quick turn test, they start scaling the HP down until it can perform the test at 100%. This is the reason why certain boats, although they look identicle to other boats, can have lower HP ratings. In the Case of the Lund Impact 1775 and the 135 rating, that boat hull is identcal to my 175 Competitor however, looks are obviously deceiving. I assume that my competitor performed correctly with a 150hp on the quick turn test whereas the Lund Impact did not thus forcing them to drop HP to a satisfactory mark. I beleive they used the 135 model simply because they knew that there really isn't a 4 stroke option between 150 and 115 (besides the 140 suzuki).

Hope that helps.

Mike I don't know much about the subject. My bil sold boats for years. He once mentioned to me that using hydraulic steering allowed an increase in HP that could be used. Of course this was done by the manufacturer. May have something to do with the quick turn test Rich is talking about. Just another question for you to ask.

Danny, If memory serves me, anything 150 or over now requires Either teleflex or Hydro steering.

I do know that some boat manufacturers are installing hydro and automatic trim tabs on their boats in order to increase the quick turn test.

Is your Lund a welded aluminum or riveted?