Codeman said:
Ok the boat is an old (read lightweight) 1848 and has a 1976 50hp Mercury with a tiller handle. At this point it is an empty hull. I have cleaned up and sharpened the impeller but the liner is grooved pretty bad and I know it needs to be replaced.
I’m no expert here either and can only offer personal experiences though for the most part I would agree with turne032. Though I think the definition of “huge difference” is relative to the user I absolutely agree with the balance. I also agree with the use of aluminum where possible.
My rig is an 1852 with a 60/40. I run a GPS on board at all times. On a lake, with no current and a typical load for fishing, I see speeds between 29 – 31 mph at WOT. River current makes a bit of difference as I have hit as much as 35mph heading down stream and as little as 26mph heading up…depending on the conditions.
When I add or remove small amounts of weight I see differences but typically nothing to be concerned over. For example, I remove approximately 100lbs (maybe more) worth of batteries and anchor from under the front deck of my boat. I gain at most .5 mph. A full load of fuel weighs about 100lbs…I know for a fact I see less than .5mph difference between full/empty.
During my recent trip to Taneycome to fish a trout tournament we GPS’ed the boat with a full load at 27.5 mph on still water. This included myself (230lbs), my partner (260lbs), 2 batteries, 12 gal fuel, 2 (large) fully loaded tackle bags, at least 15 rods, 2 20lb anchors, one 56qt cooler loaded w/food & drink, 2 livewells full of water, 1 20lb propane heater and enough cloths to keep an eskimo’s *** warm. Though it took a few more feet to plain I didn’t think a top end loss of 2-3mph was bad at all…considering I was carrying at least 450+ lbs additional weight vs. “normal”.
If I were you I would get your liner replaced ASAP. Your boat being a 48” bottom and having nothing in it leaves me scratching my head as to why it only runs 23mph. I don’t know much else about your rig but IMO my boat has to be heavier than yours, not to mention it is 4” wider, and my old 40/28 Johnson would push mine at 23-24 WOT, this was with 3+ years on the impeller and liner.
Are you sure your engine is getting up into the 5200-5500 rpm range? Have you checked compression? You might also adjust the engine up/down on the transom.
Toby