Sea Ray Sundancer power question

[ccustomrides]

So I purchased a 1988 Sea Ray Sorrento 250 with a 5.7 alpha drive this spring which I think is a Sundancer just with a sorrento name. I had the engine checked,compression and everything else came back good. I did few things to it and splashed. Well I had it out once when I first splashed and it was me and my dad and it ran great with no problem getting on plane. 1 month goes by and few days ago I took the boat out with 6 people on board including me. Few coolers and half tank of fuel. I clear the no wake zone and punch it. Next thing I see is my throttle is maxed out and I am not getting on plane. It was just going super slow. So I am not a newb so I told half of my friends to go in the cabin to help the old dog get on plane. She gets on plane and then I started to add tab to it help bring the bow down. I look on gps and I am only doing 16mph at WOT and tabs in. First time I took the boat I didnt have my gps with me so have no clue how fast I went but it was way faster then this last time. On the way back I had to move everyone to the front again to get on plane. I played with the tabs and I got it to go about 18 mph and 4100 RPM. It did go up and down few mph and rpm from weight shifting few times. So first thing that came into my mind when I got back to the dock was man this thing is way under powerded. Next was maybe I have a wrong prop. I never checked to see what was on it. I know it was a 3 blade with no dings but no clue on the size. Spare prop that the old owner gave was a 16x16 3 blade. So maybe prop on the boat is the same size. I did go on Sea Ray website and found out that the size I need is 15.25x15 pitch. So I will try to check the prop on the boat and try to repalce it if its the wrong type.
So people with same boats or same size and power plants. Are the 5.7 just way under powered when you start to put people on them or weight/load.
What is the typical speed mph loaded and with few people for boats that size with 5.7
Is it normal to shift weight when loaded and trying to get on plane
last but not least any tips or tricks to plane faster with 6 or more people on boat.
Thanks.

 

[Silly Seville]

Re: Sea Ray Sundancer power question

Yes, that is a Sundancer. You are piloting a very heavy boat. There is no such thing as "punching" it. It is not a ski boat and you gain nothing by abusing it with a heavy hand. There is a reason that the 454 was an option on this boat. While the 350 has enough "power" to push the boat, it will not perform to your expectations when you have it loaded to the max. You did not mention how heavy your passenger load was, nor did you mention how much water you were carrying (fresh water, head, water heater) nor how many batteries, or how much gear, (tools, toys, clothing) How big are your coolers? If they are the kind two people can sit on side by side, those filled with ice and food can weigh over 75 pounds each. Just based on the list I mentioned, and adding your fuel and number of people, I would say that you absolutely had the boat maxed out. Now, if you were not running the correct prop pitch and diameter, or had a prop hub slipping, or have incorrect drive gear ratios, that would immensely exacerbate the problem. You are correct about the prop size required for your boat. And you are correct about moving folks forward. And you were correct in using tabs. What I think you misunderstand is, the boat will never act like a bowrider under these circumstances. It may seem like a terrible disappointment to have bought a boat that seems to perform so slowly, but it is a cruiser. Have you had the boat weighed? I can assure you, without any equipment on board, it will tip the scales at over 6k lbs. If there is any chance that your transom is waterlogged, or you are carrying water weight in your forward bulkheads or bilge (have you checked) then you a compounding the problem even more.

So to answer your main questions...yes, the way you had it loaded with a single 5.7, it will be a "dog" on the water. What is a "few" people? You have to be more precise with your question, as even a single fat person can change the dynamic loading of a boat to affect speed tremendously. (Remember, when these boats were made, the average American adult was 150 lbs.) Just look at your weight loading placard! I think they have revised it to insist that an average person is now 180 lbs. which is still being overly optimistic!
There are no tips or tricks that I can think of that will get you on plane faster. Correct drive ratio, correct prop, correct weight loading and correct use of the throttle and drive trim/tabs is all you have at your disposal.

 

[Chris1956]

Re: Sea Ray Sundancer power question

I see lots of boats in the 25' size range with a single 305 or 350 SBC. I have only ridden on a few and they were dogs. Even a 30 footer with twin 305 Alphas is a dog with 6+ in the cockpit. We always had to put some in the cabin until we were on plane.

Your boat sounds worse than most however. You might look at the condition of your prop. That boat should hit at least the mid-20's in speed, once on plane....