Load and Prop 45C Gina Marie

[Gina Marie]

Hope all had a great weekend, we spent it traveling to Turnberry in North Miami, this was our first trip. All the work that had been done on the vessel from hull to new isenglass was well worth it and we were excited.

The Mechanic that I used was excellent and the many days we spent on the boat preparing went flawless. Thanks to Ted.

One issue did arise:

The 45C when purchased was sea trialed with 1/4 tanks full and really no water or waste. Engines were at 1900 RPM @ 17 Knots. This was the cruise speed. No smoke and a smooth ride.

The props are 26 square with no pitch.

The vessel now had 3/4 fuel on board full water and no waste. But the boat now had a full refrigerator, ice maker six people with all luggage, new kitchen granite and many other upgrades to make our lives on board more comfortable.

Now the boat still had 1900 RPM but we barley reached 12 knots, and we were blowing a little smoke.

Do I start with pitch, do I change to 4 blades. What is the correct procedure to get back to 17 knots based on my new load.

Thanks Tom/Gina Marie

 

[Captcoop]

It sounds to me like your problem is more than load. The fact that you turn the same RPM and loose 5K would indicate that you have drag on the hull. Check the bottom before you start bending props. Good Luck

 

[Genesis]

Something is SERIOUSLY wrong here.

5 knots?! WOW! Check the props for massive oysters (yes, they can grow FAST) first - if so, don some scuba gear and grab a nice stiff scraper blade....

Second, 26x26 is too much on that boat. Hatt liked to send them out with 26x28 with 500HP engines, and that was WAY too much. I had 26x26 and it was JUST BARELY ok with light load. I'm repitching to 26x25 (have the spares done, need to pull her to swap them)

It'll probably cost me a knot, but will make the boat safe to run fully loaded at 1900 without overloading problems.

This assumes you're in the 500HP range on the engines.

 

[Gina Marie]

Genesis, thanks for the reply. If I added additional weight with a combination of fuel,water and upgrades, would I not have to compensate in pitch. I will check friday on what exactly my blades were set at when I had them done in March. But my example would be a truck running empty then full once full he would apply more throttle burn more fuel.

 

[double eagle]

hate to tell you this but................
this is the way most brokers and owners make their boat seem to run better
on sea trail by taking a lot of weight off of the boat...
you should have marked the water line ...and then after you load the boat
check it again....wow you will be surprised...
have change the stripe on mine [ 58yf ] 2-3 times ...especially when you load for the bahamas,.....
my 2 cents

bill....double eagle 1972 58yf

 

[Gina Marie]

Thanks yes this could of happen. The survey although gave me en excellent report on the engines is pitch the answer???????????????

 

[Genesis]

Well, yes and no.

Brokers are known for running sea trials with about a half gallon of fuel on board, empty fresh and black tanks, and every thing that is not nailed to the walls off the boat.

However, THIS kind of speed loss is another matter. That's way too much to be likely related to loading.

 

[SKYCHENEY]

If you were just on "the edge" of planing, then dropping off of plane could actually be a reduction of 5 knots just due to weight. Think about that old 9' boat that you had as a kid-----remember how you had to lean way forward to get it up on plane (or tape a stick to the outboard handle). Weight and it's distibution can make a big difference.

 

[Genesis]

My 1985 45C will plane at 13 kts if I have the tabs full down, and that's at about 1600 RPM. Typical speed at 1900ish RPM is 18kts fully loaded. "Fully loaded" is defined as full fuel, full water, and a half-dozen technical divers with gear on board (that's a LOT of gear; each set of doubles is 100+lbs each, plus deco tanks, plus scooters (75lbs each), plus plus plus plus. You get the idea.)

This is with twin 500 HP engines.

 

[Gina Marie]

Genesis, my blades are 26 diameter,27 pitch with a #2 Cup. I had a 26x27 with a #5 cup. I added weight and I have a tower. Should I be looking at the motors or as I have turned 1900 on the port and 2100 on the starboard.

 

[Genesis]

Your max loaded RPM is 1900 and 2100 respectively (that is, different between the two engines?)

Check the motor that only turns up 1900. First place to look is at a possible fuel restriction - check the vacuum gauges if you have them (you should; if not, you need to add those so you have a handle on filter condition) as fuel restriction will severely limit power output.

What did you turn up in RPM on both engines at sea trial?