Gulfstream 232 W/ Single Yamaha 250 4S

loggie said:
Is it common to be able to hit 23 knots with a spun prop?
I’ve owned smaller Outboards and typically when the propeller goes, I won’t even be able to get up on plane.
Click to expand...
Good question. Typically, though, a spun "hub" (the rubber piece inside the prop that connects the splined piece to the blades... kind of like the clutch on a car) will allow an engine to all of a sudden OVER rev under high load. It doesn't sound like that is your issue.

BUT... a quick check... match mark the inner splined part to the outer part... if the marks move relative to each other, the hub is spinning.

This will make more sense once you get good eyes on your prop and look at it closely.
 
Since we're bombarding you with info... IF it turns out you are trimming up high enough like we talked about and your RPM's are too high for the speed... the prop might be too small. While diameter is one measure, we more commonly refer to a prop as being big/small based on it's "pitch" - which is the angle of the blades. In theory a 17" (inch) pitch prop will make the prop go forward 17" for every one revolution. There is slippage and blade design/etc that comes into play so you don't really get 17". But you get the idea. Think of pitch as the gears of a car and it makes more sense.

So, it's "possible" that the old owner always ran with a lot of weight in the boat and was much more concerned with staying on plane at a lower speed and put a lower pitch prop on there.

There will be marking on either the side other prop or around the hub (near the nut) that will tell you the pitch.
 
loggie said:
The engine has always been trimmed all the way down as far as it goes. I didn’t know any better. Now that you explained how/why to trim the engine, I see how it could be affecting performance.
I’m hauling the boat tomorrow and will see if I can have the bottom paint completely stripped. I’ll also report back on the propeller condition and specs.
Is it common to be able to hit 23 knots with a spun prop?
I’ve owned smaller Outboards and typically when the propeller goes, I won’t even be able to get up on plane.
Click to expand...
This thread reminds me of when I first put my Grady in the water. It was 2020, so covid, so I was solo and didn't know what I was doing. At all. The hull truth had told me that the 228 was a really soft hull, I was gonna love it. I put it in the water, lowered the engine, but left it trimmed way back so it shoved the bow up. I had no idea that trimming the engine correctly was important. I wasn't stupid, just had no experience. Went out with it like that and with the bow pushed up it pounded like crazy. I had a sore back for at least 4 days after that. Went back to the hull truth and said "you guys said this was a soft hull, it beat me up so much that I can barely walk." They said "did you trim the engine?" and I said "did I what the what? What's that mean?" and proceeded to get educated.

These days I feel the trim. Like Dennis said, watch your mpg or however you get the most detailed view of your fuel flow. You can get optimal trim by playing around until you get the most flow. It varies where that is depending on conditions. On a really flat day, with no tabs down, trimming it back quite a bit slides you home on the back of the boat. A good mpg for me is 2.2-2.3, but on a flat day, trimmed back, I get 2.5.

Over time, the trim becomes instinctive. If I'm on a following sea with the swells close together, that's when you could stuff the bow. I never have but I get so that the swell I'm coming into will slap the underside of the bow pulpit. My hand just reaches for the trim and I tilt back enough to lift the bow and stop the slapping. It's done before my brain catches up and says "lift the bow", it's literally instinctive.

And then you start playing with the trim tabs, that's another wrinkle. I'm getting close to being able to adjust those by feel. I can feel it when they are too far down, especially if they aren't the same amount down, they will turn the boat (which is useful to practice, if you lose your hydraulics, you can steer the boat with the tabs enough to get home, docking will be a mess, but you can get home).
 
On original SX motor props, you have to remove the prop to see its specs which may be stamped on the inside of the back (facing the gearbox) flange. On the outside of the hub, you may see something like17M. That doesn't tell you the full specs
 
I again know that it's not an apples to apples comparison here... but I took a video on my phone last summer of myself cruising, of which I was at right around 22 mph @ 3,700 rpm and burning roughly 7.5 gph of fuel. I rarely touch the trim tabs unless the conditions require it, but usually leave the motor height at around the "2-3" range on the gauge. For going WOT though, and as mentioned before, I'm at around 43 mph and probably just under 6k rpm, but in order to do that with the transom bracket on the boat, I tilt up the motor considerably. With some experience in doing so, you'll be able to hear the rpm's adjust as well as feel the boat going faster when you've found that sweet spot. Honestly to me it just sounds like the boat is underpowered, as mentioned before I'd check and see what pitch/size of propeller you have on the boat and then go from there. That being said, here's another post about a 232 Gulfstream with a single F225 on it and per the numbers halfway down on the page, it hit 39 mph @ WOT. You can always call or email Grady White directly and they should be able to send you the performance data sheet for your boat with a single F250 on it and compare your numbers to it. That being said, if you're only getting a maximum speed of less than 30 mph @ WOT, my bet is you've either got the wrong prop on there or something else is considerably wrong.

fshnfool

Thread 'Perfomance data on 232 with a 225 4 stroke'

Does anyone have any performance data on 2003 or so Gulfstream 232 with a 225 4 stroke yamaha? I have seen some posts that suggest a single engine for a 232 is a bit underpowered for that boat. I did look on Grady's website but couldn't find anything.
 
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