Originally Posted by prairie tuber
For a given outboard power and a given SIB length, an inflatable 'v' keel will require more 'strongarming' of the tiller to keep it tracking straight than a futura hull. A straight catamaran hull will require less still. If you are wondering about the differences in these hull designs, there is an expalanation of them here; Small rib vs large SIB
. Also, when comparing different lengths of SIBs that have the same general hull design, the shorter the hull, the more effort you will have to put into the tiller to keep going straight.
For example, when I put my 40 hp outboard on my 4.2m zodiac SIB with an inflatable 'v' keel (which is it's max hp rating), it requires alot more effort to keep it straight than when that same outboard is on my 4.7 m Gemini with the catamaran hull (see picture below). This is because of both the difference hull length and the difference in hull design. With the 40 hp outboard on the Gemini, it takes minimal effort on the tiller to keep it going straight while on calm water, and moderate - substantial effort when going thorough strong or whirlpoooling currents such as below.
Hello again Prairie Tuber
Yes, after your previous advice I've been trying to find out more about the types of hulls you refer to. They sound ideal for my situation - slightly nervous kids - but haven't been able to find many options with speed tubes. Are they pretty unique to the Zodiac Futura models and the faster racing-type cats?
Mind you, the prospect of meeting any of those whirlpooling currents doesn't exactly fill me with joy. Looking at all you fantastic pictures, though, I suspect you approach to RIBbing is somewhat hardier than what I am planning!
Happy Thanksgiving, btw. (Or is that just an American tradition?)