115 or 150 mercury optimax?

[fisheymikey]

Good morning,

i have a 18.5 deep v trophy center console it weight about 2000lbs

i use to have a Force 125 on it that weighs about 300lbs that the piston blew right thru the engine block!!!

due to the season just started im going ahead and buying an optimax now the question is i found 2

both are 2006 one is 115 that weighs 375 the other 415

the boat is rated for a 135 max but after redoing the transom and stringers and the fiberglass has been reinforced at leas 2x more stronger due to thickness also using BIAX fiberglass therefore i know the transom could handle it. my only concern is the extra weight in the back might not be good for the balance.

i fish mainly in cape co that the currents and waves are pretty aggressive. I need you gurus advise what to do due to the significant investment.

All the help and suggestion are going to be greatly appreciated.

 

[Chris1956]

I would think the 115HP motor should handle the boat as well as your old Force. If that was acceptable, I would go that way. The larger motor violates the max HP regulation, and the Federalies may not like it.

 

[ondarvr]

The strength of the transom has nothing to do with the HP rating, it's the hull design. The weight difference will have little effect, I'm not going to comment on over powering

 

[fisheymikey]

ondarvr: i like to to follow the rules also but i think the guys from bayliner did not factor the variables very well in regads of the design of this hull. the deadrise is 22 degrees and it displaces alot of water thus the reason it takes for ever to plane with the old 125 force. the 135\150\165 is all the same engine block.

if someone has any details how a company rates the motor hp please advise.

i also am leaning towards the 115 but just want to make sure the HP is enough for this engine

 

[ondarvr]

The Coast Guard has a formula to calculate HP, it's around here someplace.

 

[SparkieBoat]

I tend to over horsepower my boats because 30 MPH is just too slow for me. I have found that it is usually not an issue so long as you do not go stupid with it. I would go with a 150/175 on an 18.5 deep vee fiberglass boat all day long. I mean really is 15 or even 40 HP more going to cause your boat to break in half or something? The 115 would be a little on the slow side for that boat probably lucky to break 32-35 mph. I mean 135 max on an 18.5 boat sounds under rated to me anyway. I am not sure why so low. any fiberglass 18' deep vee boats I see are 150/175 rated, some 200-225.

 

[jimmbo]

fisheymikey. don't worry about putting the 150 on your boat. Up here in Canada there are no rules or restrictions against exceeding the recommended Horsepower. Just be sure your insurance policy states there is a bigger motor. If the insurer is aware of it, and they accept your money, they are covering you

fisheymikey. ne vous inqui?tez pas mettre le 150 sur votre bateau. Jusqu'? ici, au Canada, il n'y a pas de r?gles ou de restrictions contre d?passant la puissance recommand?e. Juste ?tre s?r que votre assurance politique stipule il y a un plus grand moteur. Si l'assureur est au courant, et ils acceptent votre argent, ils vous couvrent

 

[fisheymikey]

well im going to pickup the 115 tonightthe price too good to pass up 3700 with only 300 hours on it

is there a way to verify the number of hours on the engine without bringing it to the dealer?

i want to do a compression test is there way to do so if i dont have the controls?

and would it harm the modules or coil pack?

thanks guys and merci jimmbo

 

[SparkieBoat]

I would recommend taking it to a mercury mechanic and have him look it over and give you a computer print out which will include the hours.

 

[SparkieBoat]

you can spend hundreds and hundreds of dollars even thousands on repairing those optimax motors quickly. best to have it checked out by someone who knows what to look for,

 

[fisheymikey]

ok guys DONE!

made the purchase and i am going to bring it to a mechanic the only reason why im reluctant is the mechanics here i caught them a few times being less then qualified. the ppl here on iboats are KICK@ss.. help me a ton with my old force 125.

Can you recommend me the the best downloadable PDF service manual for these optimax 2006?

thanks guys

 

[SparkieBoat]

I do not know of a PDF file, but I will tell you this much, unless the last owner has paper work to show where he just had the injectors cleaned and flow tested recently...I would send all 12 to a place that will clean and flow test them. The cheapest price I found was $300 plus one way shipping, but there is a well known place that it is about $380. A modest investment considering the danger of clogged injectors. Careful pulling them out if you do it yourself, those air injectors can get stuck and you can ruin one if you are not careful. they are pricey even used. also clean out the VST chamber and clean the filter at the bottom of the high pressure fuel pump.