Quote:
Originally Posted by Slo Poke1
I've seen some intriguing performance discussion around here for the Etec 90 on a 20 footer. Also, added performance discussion regarding brackets. Which would have a greater impact on performance with the Etec 90 on a 20': a bracket or hydraulic jack plate? If one went with a 14" jack plate, would that forego the need for the added performance from the bracket?
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The "added performance from a bracket" claim is misleading. The reason you might pick up 2-3 mph in WOT speed with a bracket is that it shift's the CG aft by about whatever the setback is. That makes it easier to get the bow up to reduce wetted surface and drag in flat water. What the bracket makers DON'T tell you is that, UNLESS you rebalance the boat by moving gas tank, batteries and console forward enough to eliminate the CG shift, adding a bracket will significantly increase your min planing speed and hurt the ride!
Although I added a galley seat to my Seafari that added a little weight forward of the CG, I couldn't move the gas tank and of course there is no console to move. With the old 300 lb motor on the transom, I could easily plane at 12 mph. Initial trials with a new 429 lb motor set back 30" on a bracket, my min planing speed was up around 22-23 mph, which is absolutely unacceptable! After adding a stern lifting 4B prop and a Doelfin, I can again plane at 12 mph, but I'm sure those 2 items COST me more WOT speed than I gained with the bracket! A good friend of mine with the same boat just repowered with the same motor but no bracket, and he's at least 5-6 mph faster @ WOT! I don't really mind because I never run WOT, the boat rides great, still averages over 4.0 mpg, and I like the extra room and big swim platform. But if you're thinking of adding a bracket just for another 2-3 mph top speed, just recognize that there is a risk of losing more than you gain if you screw up the boat's balance! And a jack plate can still cause the problematic CG shift, but without providing the benefits of a swim platform and a big flotation tank to maintain static trim for self bailing at the dock!
Bottom line is that adding a bracket on a 20 is not as simple as it looks and requires some serious thought and modifications to do it right, which is why we made my Pros & Cons thread a sticky in the Repairs/Mods section!