Viper/Evinrude 115

Hi, my name is Ronny Jetmore and I just signed on to become a member with you guys.  I just purchased my second H.S. last week.  The boat is an '84 Viper with a '78 Evinrude 115 without powertilt.  For starters, can you first please tell me if it is true that the Mercs are better on light boats?  I have taken the boat out once now and it really runs strong.  It has a very balanced and smooth ride to it.  For whatever reason, my old Viper with a 115 was not quite as smooth.  Anyway, what speed and handling recommendations would you make for a guy that does not have buckets of money to spend because of a new business venture?  I believe the prop is a 13x19 and is stainless.  It turns about 5,900rpm, which I know is a bit high for a Johnson.  How fast would this boat go with the current power?  Would I be better off looking for a different motor?  Is a jackplate beneficial to this boat?  My previous Viper had powertrim but I think that on top end I am running about the same in both rpm and speed.  I assume the motors are at the same angle.  The only area that I really miss the powertrim is when taking off-The boat has a tendency to cavitate (I guess that is what it is doing-winding up so that I need to back off until it reaches plane).  Believe me, this boat really feels good in the water, but any input would be greatly appreciated.  I read that be wetsanding the bottom with 1200 grit, you can pick up 1-2 mph.  Is this so, and is it worth the trouble?  Please let me know about which make and model of prop to go with.  I used to own a 13x20 Raker, that really seemed to help, are these good?  Regarding caring for the boat: It has slight (very slight) oxidation, what do you recommend?  The transom is solid but I don't know if the holes have been sealed properly.  I attribute the solid transom to the fact that this boat has seen very little ride time.  Also, what are your thoughts on how to set a trailer up, do you like ez load style or are they too hard on the bottom?  The only issue that I see with this boat is the fact that on one of the passenger side strakes (I guess that is what it is called), closer to the front, probably about even with the windshield, a notice a minor and gradual indentation that is about 6 inches long.  I suspect that this was where one of the rollers used to rest.  I don't think that this will cause much of a handling issue, being as, at high speeds, this part of the boat does not spend much time in the water.  Please tell me your thoughts.  I am really sorry for asking you so many questions, but I have no one else to ask.  How much power is too much power on one of these?  It seems that many of these Vipers that have 175's and above, are not as fast as V-Kings with 175's.  Is this because of the hook.  Why does the hook exist?  Thanks again, I promise that I won't play "one-sided 20 questions" again!  Thanks, Ronny Jetmore




I'll do my best to answer your questions. On your viper the Merc's are really no faster than the OMC's. To be honest horsepower is horsepower and while the motors are different and may require different set ups, the results are about the same. First thing on your shopping list should be a power trim. This will allow you to take advantage of future good props and such. A jackplate is the last thing on the list and even then a good viper/115 will run 70ish without one. Old 14" Merc choppers that were rehubbed worked great in the 24 and 22 pitch range. More current props would be the Yamaha drag props or a copy by some of the prop shops out there. We used to sand the bottoms of race boat but we usually never went finer than 400, most of the time 220 grit. The idea is to create microscopic scratches to break up surface adhesion. The oxidation has to be sanded out then buffed. That's the only real way to fix it. Go with bunks on the trailer. If you don't have them on the trailer now, put them on. The hook is in the bottom to pop the tail loose or lift it so to speak. With limited power it helps. That is why with a V/6 it is slower than the flat pad V-king. With big power it compromises the ride attitude.  

Hope that Helps.




Please submit whatever questions you have to  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Mark C.


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