I just received a copy of Power Boating Canada, Volume 23 Number 5.  There was an article from a fellow asking about motor and boat size of his 1996 Invader Bow rider model Mirage 170 with 115 hp Johnson.
            I had a 1980 Delta Craft 170 ski/speed boat.  It was rated for 140 hp.  I bought it new in 1980 with 140 Evinrude Sport, then I put a 175 hp Evinrude on it.  What a difference it made.  The 140 hp was good, it handled nicely, maximum speed and power depended on props.  The 175 hp had much better speed and handling was excellent.  
            In 1993, I traded the boat for a new 1993 Campion Allante 170 open bow.  Now, this one was factory rated for 112 hp.  This boat was a lot wider than the Delta Craft, yet only rated at 112hp.  I ordered it new with a 175 hp Evinrude Intruder.  I finally settled on a transom lift kit and a 25 inch, chrome raker prop.  I got a top speed of 65 to 70 mph and it handled the extra power really well. 
            In 2001, I put a foot throttle and dual steering wheel trim controls, hydraulic steering and a 2000 Mercury 225 hp Offshore, ported out to 250 hp.  I wanted speed and I got it!  Top speed with 3 adults was 75 to 78 mph and by myself I was able to obtain 82 mph.  I loved it.  
            Not much of the boat was in the water at that speed.  The boat had power, speed and excellent handling.  But, you need to drive with common sense, I never messed around at that speed and not just because there are no brakes on a boat.  In my opinion, a boat and motor size depends on the person or persons who drive the boat.  I know not everyone is into that kind of speed, but any boat driver needs to have common sense even if it is only 115hp on a 17' boat.
I just thought I would tell you my story.

                                                                        L. George
                                                                        e-mail

            Thanks for the story of your experience.  I too have “overpowered” boats to reach speeds in the 70-80 mph range.  I also agree that with proper set-up, and even at speeds in excess of 100 mph, people can learn to drive boats safely.  The problem is that the degree of set-up becomes extremely important as speeds rise above 50 mph and the experience to drive safely needs to be acquired.
            The Delta was a great hull for a basic learner as it was so good right out of the box, but not all hulls can handle this well.  As you moved up in size, you realize the need for things like dual steering, trim controls, foot throttle, etc., all of which point to the fact that keeping both hands on the steering wheel is essential at all times.
            You don’t mention “chine walk”, but you must have experienced this in your quest for speed.  This is the tendency of the hull to fall over slightly off the center V as it becomes higher (less wetted surface) as the speed increases.  When this happens the chine touches the water and throws the hull back up and over to the opposite side and the other chine hits the water and repeats the whole sequence again, usually faster and faster until you back off on the throttle to lower the speed and restore the balance.  Chine walking is one of the scariest things that a new owner of a higher speed boat must deal with.  Having a wide pad at the aft end of the V helps this as do properly mounted and adjusted after-planes.  No-play steering systems and solid engine mounts also help.  This is not the territory for a new boater by any stretch.
            The point is that some boats, and more specifically some hull designs, can be made to handle the extra power, but some are easier than others.  While learning the curves can be dangerous without a certain degree of caution, you certainly seem to be taking the right approach.

You answered a question for a reader and advised him to buy a 4 stroke outboard because of the water depth at his cottage.  What is wrong with a 2 stroke?  If I was buying a new outboard I would buy an Evinrude E-TEC.  Everyone is being fooled with this 4 stroke phobia.  Do not downgrade a 2 stroke, check out the tests.

                                                             R. Sutton
                                                            e-mail

            I do not have a problem with the 2 stroke engines, but I really mentioned the 4 stroke because the reader was thinking of buying a 4 stroke stern drive.  I wanted to let him know the outboard is a better option if it has to be left tilted up because of shallow water.
            Stern drives do not like to be left in the up position for long periods of time.  It can cause damage to the rubber bellows that covers the universal joints and the shift cable, not to mention that muskrats can chew a hole in the rubber and sink your boat!
            As for the future of 2 stroke verses 4 stroke, one only need look at the automobile industry to see there are no longer any 2 stroke automobiles on the road. 

            I have a 1989 250 Cadorette with a rebuilt 350 cid engine.  Changing props will not change the maximum rpm.  The best it will rev up to is 3900-4000 rpm.  I was told I might have the wrong gear ratio in the stern drive.  What do you think?

                                                                        P. Henderson
                                                                        e-mail

            Well it is possible, but not too likely, that you have the wrong gear ratio.  Assuming that you have Mercury Alpha I drive and a 260 hp Mercruiser unit the smallest propeller you can use is about 15 pitch and you can not get over 4000 rpm at best?  Then I would say the engine is not putting out its maximum horsepower.  If the problem occurred after installing a rebuilt 350 cid assembly then I suspect that the rebuilt engine is not exactly the same as the 350 cid unit that you have replaced.  Perhaps it has a different cam, pistons, compression ratio?  This would be especially true if you used an automotive rebuilt unit rather than a marine unit as they have a much lower compression ratio as well as lighter duty components and steel frost plugs, among other differences.  These automotive rebuilt units will almost always give inferior performance compared to their marine cousins.
            Having said that; 3900-4000 is just a bit below the recommended range, so you could have your propeller re-pitched two inches less than it is now and gain approximately 400 rpm.  This will not necessarily make the boat go any faster at the top end in mph, but should make a difference in “out of the hole” performance.

GOT A QUESTION, A PROBLEM OR DO YOU NEED SOME SERVICE INFO ON SOME MARINE ENGINE OR EQUIPMENT?  SEND ME AN E-MAIL AT  stephen.horsfall@sympatico.ca OR FAX ME AT 1-613-236-0700.