Over Powered?

[ob1jeeper]

Re: Over Powered?

wilkins,<br />ob just hit the nail SQUARELY on the head... As an engineer, you should have understood the theory behind "factors of safety". THUS, anyone to advise you to exceed these is exactly as ob points out, irresponsible...<br /><br />And PLEASE don't lump all engineers into the pile of those who like to argue, just for the sake of argument. That is Definately NOT what engineers do (at least in my line of work)... The engineers I work with, gather factual information, then make sound decisions based on that data.<br /><br />Somehow, it seems you have being an engineer confused with being a lawyer (or politician)...<br /><br />By-the-by... Glad to see you FINALLY made the GOOD decision to not use the 200 on this hull. Wish you had used your engineering powers of observation and listening, to NOT make this such a difficult thing for so many. THAT part was simply not being an engineer, nor necessary.<br /><br />Good Luck, Obiwan Jeeper

 

[93bronco]

Re: Over Powered?

wilkin-bravo!!!!! <br />you know after this you mite find no one will answer your future ??'s.<br />anyway ill respond to this. i bought a 1994 1802 (18ft) bayliner trophy walk around which had been converted from the original force 90hp to a what turned out to be a 175hp evinrude. the hp sticker had been scrapped off and i didnt know the difference. but its only rated at 125hp. i called bayliner and they werent worried about the hp, they were worried about the weight of the motor.<br />heres the nada hp/lbs: all have 25inch shafts<br />1994 force -------- 1994 mercury<br /> 90hp -- 249lbs ----- 125hp - 315lbs<br />120hp - 284lbs ---- 135hp - 404lbs<br />150hp - 336lbs ---- 150hp - 395lbs<br /><br />1982 envinrude that i took off:<br />175hp 385lbs<br /><br />the funny thing is that when i went to look up the hp rating at the local dealer there is no listing for my 94 1802 trophy it starts with a 95 model rated at 125 hp and there was another listed for 150 hp. same model 1802. confusing, (to me anyway) because a mercury motor was an option and looking at the weight the 150merc weighs more than the 150evin, using the 150hp max.<br />using the 125hp max rating it is obvious why weight is a concern <70 to 100lbs> thats alot of weight. now it gets really confusing: <br />-<br />i find the motor that i want- a 120tx johnson, so i called the dealer and have them look it up, they told me that motor would be fine ???? that motor weight was listed at 365lbs (actual is 378 by omc manual), 20lbs less than the 175hp i was told was to heavy for the boat. talk about being frustrated and confused.<br />-<br />now the trophy's are built better than a regular bayliner < and i really like bayliners > but i was a little apprehensive about the weight thing.<br />i have a friend who had 16ft capri w/ 85 force til we hit a pot hole and the motor snapped down pushing into the hull. transom was rotted.<br />to be safe on mine i installed a 1/4 alum. plate between the motor and transom (that also let the motor ride flush and not on top molding) along with two 1/2in thick bars supporting the other sides. (upper & lower bolts) that is alittle over kill but i feel safe in knowing that the motor is not going to break through the transom.<br />bayliners are good for having bad transoms, if you are serious about overpowering make sure you redo the transom for your safety , others and the environment.<br /><br />forgot- when i got the max hp sticker i ordered for my HIN # its rated at 150hp max. who knows??

 

[wilkin250r]

Re: Over Powered?

I finally got the chance to make some good measurements today. I found out my boat is a 19'! The transom is in great shape.<br /><br />So, with this in mind, do you think 125hp will be enough to pull me out of the water on a single ski pushing a 19' bayliner? 200hp may be a little overkill, but I'm skeptical if 125hp will be enough.

 

[JasonB]

Re: Over Powered?

A 115-125 will if it is proped right. AS stated earlier, carry 2 props. One for cruising and one for skiing. Also, I would shoot for a motor that is 115-125 at the prop shaft, not at the flywheel, ie. made after 1984 or so. <br /><br />As in my earlier example of my 1976 85hp Johnson, it is probably only 75-80hp by today's standards, but it can still haul up skiers.

 

[Kenny Bush]

Re: Over Powered?

Man Wilkin, I did not think this subject would get so much attention........After seeing that your boat is 19', I would think you would be OK with the 200. If the motor is a Merc, the weight will be allright. 135 up to 225 HP use the 2.4 or 2.5 liter blocks and all dressed out weighs about 400 lbs....I think if you put this motor on, you will need a transom plate(this will help distribute the weight out over more area in regards to stress). I do not want to upset you, but I am not a big fan of the Brunswick Bay-Rays, but even at that, I think it will hold it.....I have seen 19' bayliners with bigger I/O's on them. I put a 150 on a 16' Chris Craft that was rated for 65 hp max just so we could ski/kneeboard bihind it. I added some floatation because I feared if it did swamp, it would not float level due to the heavier motor. This little boat was great as a ski boat and still handled quite well. I am an engineer too, but some will say that is a handicap....anyway, use some structural integrety in your application and I think you will be OK. Goodluck....BushCat <br /><br />Heck....even sailors try adding more sail..........

 

[roscoe]

Re: Over Powered?

Sailers that add too much sail will end up getting wet, or dragging their mast back to shore<br /><br />No offense to you Bushcat, but I don't find it suprising in the least that the only person Wilkin aggreed with or thought was knowledgable, was the person that told him what he wanted to hear. So why did he bother asking the question?

 

[ob1jeeper]

Re: Over Powered?

bushcat,<br />Perhaps I might offer a suggestion. If you work for a company that has a legal department, you might want to check with them on your potential legal responsibilities, when offering written advice (especially that which has potential safety implications), as a self-professed engineer... If you do not work for such a company, you may want to find a corporate law attorney to explain your possble liabilities...<br /><br />Thankfully, wilkins seems to have acknowledged that motors larger than the hull is rated for is indeed not such a great idea.<br /><br />AND... as has already been said (if you had read the complete list of entries) you would have obtainded the information regarding how OB's & I/O's require differing hull structures, so your words about seeing I/O's with 220 hp, etc, is like comparing apples and oranges.<br /><br />I find it VERY odd when I read where a self-professed engineer is offering written opinions on operational safety which are outside the limits of what a federal agency have rated the hull for!! (in this case, both the hull manufacurer AND the coast guard hve placed a rating on the hull...)<br /> <br />The only way the engineers I work with would make such a statement, would be if they used factual data collected by running tests, to lobby for a change to the rating. This may be possible, but it would seem to me to hardly be worth the time, $$, and aggravation to first design and make the hull modifications necessary, then test & work on getting the hull rating re-certified/changed.<br /><br />If one were to be dead set on running a bigger motor, simply sell what you have, and move on up to a properly rated hull/motor combination.<br /><br />wilkins has enough information to know that what he needs for this hull, is to correctly prop a "rated motor" for his skiing activties.

 

[wilkin250r]

Re: Over Powered?

Ok, so why would an 18' be rated at 150hp, yet my 19' is only rated at 125hp?<br /><br />As far as legal liabilities for advise, this is a general chat forum. Bushcat isn't selling his services as a consultant or expert. I can't sue him for his advise any more than I could sue my buddy the computer tech for telling me my boat hull is in good shape.<br /><br />If I ask an expert at the local boat shop, legally they cannot give me advise on exceeding the ratings of my hull. I joined this chat forum specifically because I can get unbiased opinions from some knowledgable people without the problems of legal issues.<br /><br />Ok, let me add some more fuel to the fire. I don't understand why an 18' bayliner trophy can be rated at 150hp, but my 19' is only rated 125hp. Would there be this much opposition if I want to put a 150hp on it?

 

[wilkin250r]

Re: Over Powered?

SO, is Mariner a good brand?

 

[93bronco]

Re: Over Powered?

i think they sent me the wrong plate.it should say 125hp max.<br />but the 1988 18ft cobra <actual 17.5ft> was rated at 125 max also. i agree that the 19ft should atleast be 150hp. good luck at what ever you decide.

 

[Kenny Bush]

Re: Over Powered?

Well Wilkin, now everyone is questioning my integrety.....But as a Mechanical Engineer for the number 2 Missle Defense Contractor for over 23 years, I will put my work up against anyone....Its up to the individual to accept or reject the information given on this board....I have 7 boats in my arsenal, 4 of which have been modified in the HP department. Wilkin, as you can see you have many different opinions to choose from which is exactly what you came to the board for........Most of these individuals are just following the "fence lines" of society, and it is up to the "trailblazers" to push the paradigms of mankind to new frontiers.........I know I could make that 200 work, but then again, that is why some of these people are stuck on the bank. I would check with you insurance man, because sometimes it will affect your coverage. Best of luck......BushCat<br /><br />Hey Ob-jeep........I have a couple of CJ's I have built for Offroading.....Both with smallblock chevy motors, and 1 ton Axles...............I am sure my stupid engineering would pull anything you got in half.............but if you want to stick to water, you will be eat'n my propwash there too.....

 

[ob]

Re: Over Powered?

Bushcat,glad to hear your self esteem is in high gear,but I wouldn't get too carried away.Most boaters I'm sure would not take offense to "eating your propwash " as you put it ,since not everyone considers the fastest boat on the water to be macho.As for your Jeep which is a poor at best correlation to the topic at hand,I'm quite sure that my 72 Chevelle big block would send it whining into the garage with its tailpipe stuck between its axle.Can you also benchpress 400 lbs?<br />Maybe you could start a topic in the NTDWB forum and continue your monster machine crusade.You might be surprised.

 

[Kenny Bush]

Re: Over Powered?

OB, my reply was to OB1jeep........Ob you have allways given sound advise....Dont pick on me with that chevelle..........My 69' Z28(62000 original miles) just might come over whip that heavy chevy.......but getting back to boats.......Wilkin, have you decided which way to go? If you do not use that 200, I would be interested in it(if it is a merc.). Let us know...BushCat

 

[wilkin250r]

Re: Over Powered?

Bushcat, could you give me some details about a transom plate? I've built many toys without exact plans, I'm pretty sure with a good explanation I can manage some simple reinforcements.<br /><br />Before everybody yells at me, this doesn't mean I'm putting this 200hp on this boat, I am simply asking for information. I'm actually bidding on a 125 on ebay as we speak, so there is no need to yell at me for pursuing a course of action against your advise. I plan on keeping this 200hp until I can properly test this 125hp. If I find it underpowered (yes, I will make sure it is propped correctly) I'll build a transom plate and put this 200hp on, advise or not.

 

[BassMan283]

Re: Over Powered?

It's good to be a trailblazer, unless you wind up as tomato surprise.

 

[Kenny Bush]

Re: Over Powered?

Wilkin, The transom plates I build consist of a large plate of aluminum, usually 3/8" thick. My plates cover about 70% of the transom. Basically I am spreading the inertial forces over more surface area of the transom. Without these plates, the motor bracket puts all the force directly on the transom, in the footprint of the motor.....The transom bracket will spread the force over a much larger area........Now all this said, one must take note of the fact that the transom will feasably take it. You cannot do any of this with a flimsy transom and stringer system. I would also use the aluminum brackets on the inside as well(just spreads force out over a larger area). Now, 200's dont scare me much due to the weight......They weigh as much(almost)as a 150 or 175. The main horsepower increase comes with higher RPM capabilities. If you do use the 200, I would really respect safety at about 4000 rpm's or higher because you will be in uncharted territory. Once mounted, I strap a full vest, and go test piloting. I run them wide open, hammer them in a turn, see if I can cavitate the prop, run them hard into rough water, and if all seems OK and safe, we'll come back for some fun on another day..... Anyway that is what I do and it has been successful so far. I think man has allways tried to get more power and speed out of any mode of transportation......Goodluck...BushCat

 

[wilkin250r]

Re: Over Powered?

Oh, ok. Well that sounds pretty simple, I was thinking it required not only a plate, but supporting braces down to the stringers to handle the extra torque placed on the transom.

 

[Kenny Bush]

Re: Over Powered?

Your on the right track wilky......I had to do that to one boat I had. I made two brackets that went forward about 3 feet and attached to the stringers. I was affraid the HP would twist the motor off the back of the boat.......BushCat

 

[ledgefinder]

Re: Over Powered?

Keep in mind that eBay Mariner 125 is for a 25" transom...<br /><br />The right prop pitch can make a BIG difference. I (235#) could start slalom behind our 19' GradyWhite, with an 88SPL OMC - not the lightest boat in the world.

 

[wilkin250r]

Re: Over Powered?

True, a 25" transom is what I have.<br /><br />Does anybody have any info on changing shaft lengths? I saw a 150hp johnson for sale near my house with a 20" shaft. I've seen some reference for engines up to 40hp, but I haven't seen any for the big motors 100hp and up. Does anybody know where I'd start looking?