Add'l Newbie questions

I am a complete newbie to boating. I bought an 11' RIB to use for diving and it had a 1991 9.9hp Mercury motor on it.<br /><br />The motor does not seem to be enough when the boat is fully loaded and I want to put a bigger motor on the boat. I had posted about a Honda motor earlier this week, but now I am just plain confused.<br /><br />My questions are:<br />-Boat is rated for 15hp motor. Is this really a power or weight restriction? I can find 20hp motors that weigh the same as most 15hp.<br /><br />-How much more power will I really gain with an add'l 5hp?<br /><br />-How does the engine displacement affect performance? If two motors are 15hp each and one has a greater displacement, is that good?<br /><br />-Since I am in CA, must have 4-stroke, so weight of engine is paramount. My old 9.9 weighs 77lbs. Some of the 15hp 4-strokes are 115 lbs. That seems like a lot of weight to add. What motor would you recommend????<br /><br />Is there FAQ available that would answer questions like these??? I appreciate everyone's input.

Re: Add'l Newbie questions

Wow, lots of questions. I'll try a few. First off, boats are rated for a certain hp based not only on the amount of weight the transom can hold, but also on the amount of thrust it can handle. So, just because a 15 and a 20hp motor weigh the same, it may not be a good idea to put the more powerfull motor on there unless you are sure the transom can handle it. This is to say nothing of how the boat will, or can, handle the additional speed. If your boat is rated for a 15hp motor, that's what I would put on it. You will notice a substantial increase in power with the 15hp.<br /><br />Two different motors with the same hp but different displacement will be so similar, you will not notice the difference. However, you will notice a difference between the 2 stroke and the 4 stroke motors.<br /><br />The 4 strokes do weigh more, but some are lighter than others. I think Nissan/Tohatsu makes a 4 stroke 15hp thats lighter than any other, but I could be mistaken. Also look at the Hondas as their motors seem to be a little lighter as well.<br /><br />Hope this helps, good luck.

Re: Add'l Newbie questions

The four stroke is not required for Califonia as many say. There are local restrictions in some areas which prevent use of older motors which do not meet emission standards. New (bigger) direct fuel injected (DFI) two stroke motors meet this requirement just fine. But even a carbed four stroke may not meet the standard in those restricted areas. I bought a carbed Bearcat 55 thinking I would be ahead of the polution game- I am and am not. My motor runs cleaner than any old two stroke but is still not legal at Tahoe as I have seen advertised by sellers of old boats who had this motor. Would have to be fuel injected there, still. (I like the motor so that was not any big deal to me- I don't go to any restricted areas anyway) Outside the restricted areas older motors are still allowed, just can't buy new ones which don't meet the standard. <br /> California boat motor requirements

Re: Add'l Newbie questions

Bearcat,<br />Thank you for the link!!! I now have to wonder if my local boat dealer is just trying to get me to buy an expensive 4-stroke. Guess I can do some shopping for a slightly used 2-stroke.

Re: Add'l Newbie questions

I have a two stroke 1997 15 hp Evinrude. It weighs 72 lbs and rips my little tinny out of the water! There is a big difference in power with the 9.9.

Re: Add'l Newbie questions

Ok, since I can go the 2-stroke route, what about the used Mercury's available from IBoats??<br />I would be using this engine in salt water only.<br /><br /> http://www.boatmotors.com/motorparts/index.cgi?pid=4063&flag=2