Weight vs Speed

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rickybobbybend

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As I move through the mods on my tin, I am always trying to be aware of the net weight gain. (Though I did not use aluminum framing...next time.) Buddychrist's thread (Top Speed!!!) motivated me to actually check what effect adding the weight of the mods had on top speed. The boat is a 1244 v and the OB is a '79 Rude 9.9. In each test, the total weight of driver and "stuff" on board was the same; the only changes were the weight of the modification and/or how weight was positioned in the boat. The motor was kept in its lowest position throughout. All speeds are GPS, recorded with next to no wind on the same lake, elevation 3,444 feet. The boat and motor weigh 235 pounds and the "stuff" on board weigh about 55 lbs. I scale in at 175. So 465 lbs. total.

The initial top speed was 20.2, and it seemed to take a long time to get the nose down on plane.
The first set of changes moved the battery forward and under the aft bench, the gas (3 gal.) stayed behind the behind the aft bench, swivel seats were added to the aft and front benches. And 14 pounds of mods were added to the stern area. Result, no measured change in top speed or subjective time to plane.

The second set of changes added 18 pounds to the bow in the form of a now-covered storage area. Plus I was able to move 19 pounds of cargo to the new front compartment from the stern area. Top speed was 19.7. The bow clearly came down quicker and the boat was more stable going into strong headwinds.

Using that as a base, with a passenger on the middle bench (also 175 lbs.), the top speed droppd to 17.6 mph.
With the same passenger on the front bench, top speed was 15.7 mph.

Every situation will be somewhat unique, but it was was interesting to see how weight can be your friend and your enemy. So on this rig with someone else aboard, it doesn't really matter where they sit if we are not in a hurry. But if it is a race to the Honey Hole, they go on the middle bench. Such is life with a 12-footer.
 
Good to know that your boat will still plane with two people. Speed on 9.9's can drop pretty quick when another person goes along for the ride.
 

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