340 Prop results, end of season...(video)

mnm99

Well-Known Member
Oct 2, 2015
2,445
Long Island
Boat Info
2004 340 SeaRay Sundancer
Engines
Twin 8.1 Merc
At the start of the season I posted these results ( in Blue ). I have to give an update. So I pushed it a little bit the last weekend of the season to see what she can do. I was pleasantly surprised. With calm water I was able to hit 4700 rpm with 8 people on board at 41.5 MPH... I'm going to keep the props where they are. The engines aren't lagging and I can still cruise at 30 mph at 3500 rpm.

I got some results...Very pleased so far....I can't really give a real accurate result since there was a pretty bad chop and I was heading into 15mph winds, but even then I think you will be impressed! So a recap of the first post.

"At the end of this season with 4 people and loaded normal I can hit 4630 WOT, , no new bottom paint since 5 years ago, Full tank of gas, fresh water and loaded with beer. Even with the 4630 rpm do you think I can add another degree of pitch? Of course the prop guy will advise me, but I'm thinking my RPM will drop 200 rpm to 4400 and still be good. I'd like to gain a couple MPH if possible. The range is 4200-4600.
3440 I'm at 26 mph,
3500 I'm at 27 mph. "

New results....

I can stay on plane at 18 mph was 22 before
3400 I'm at 28 mph = 2 plus gain
3500 I'm at 30 mph = 3 gain

Went from 21 pitch to 22 with med cup.
21.5 to 22.5 with med cup.

I gained 3 mph and I was still able to hit 4650 rpm at 39 mph. It was even a bit more than last year and gained speed., but really wasn't a test because it was so choppy and I pulled back quick.. The bottom paint was pretty good last year. The changes I did was add an additional pitch and balance. Boat is smooth a silk too. These results were with the same load as last year. Full tanks of gas, full water tank, loaded with beer, bedding , 2 people exc...
 
What numbers go to port and starboard? I would like to see what I have on my boat and since we have the same setup I would like see if I can get close to your numbers. I think I run closer to your original ones now. I also notice that my starboard side always seems to need a little more throttle than my port side.

I had the props conditioned prior to delivery last year to work out a vibration which is fine now but would like to see if I can tune it in a little better for speed and economy.

-Kevin
 
What numbers go to port and starboard? I would like to see what I have on my boat and since we have the same setup I would like see if I can get close to your numbers. I think I run closer to your original ones now. I also notice that my starboard side always seems to need a little more throttle than my port side.

I had the props conditioned prior to delivery last year to work out a vibration which is fine now but would like to see if I can tune it in a little better for speed and economy.

-Kevin
18x22 and 18x22.5 with a decent cup. I'll try to find my spec sheets.
 
Found the specs. I'm going to increase the cup this winter. I'm still running at 4700 RPM. Trying to get a little more out of it
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prop1.jpg
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Got my props back from the shop after this season. During checking he said I lost 1/2 degree of pitch. At the time my cup was .125. He put back the pitch to the original along with adding more cup. The cup now is at .250. I should loose 100 or so rpm. That will put me right around 4520. I'm still within my spec of 4200-4600. My goal is to get as close to 1mpg. Last year I was doing 30mph burning 32gph. I don't think this will do it, but I hope it will be close. Everyone that rides on my boat cant believe how fast it is. It's Killing me to see how she goes with the extra cup. He blasted them today and recommended coating them right away. Stored in my basement now.
11-29-2017.jpg
 
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Got my props back from the shop after this season. During checking he said I lost 1/2 degree of pitch. At the time my cup was .125. He put back the pitch to the original along with adding more cup. The cup now is at .300. I should loose 100 or so rpm. That will put me right around 4520. I'm still within my spec of 4200-4600. Killing me to see how she goes with the extra cup. He blasted them today and recommended coating them right away. Stored in my basement now.View attachment 51996
Nice! What do you coat them with?
 
Thanks! That’s what I used on the props on my old boat.
I was thinking about trying Prop Speed, but it looks like it is a lot of work.
 
Thanks! That’s what I used on the props on my old boat.
I was thinking about trying Prop Speed, but it looks like it is a lot of work.

I have had Prop Speed on mine and it lasted a couple of seasons for me. It is a very expensive product and process to have done properly as it requires two people for the two part process and the second step has to be completed within a very short period of time.

The concept is that it make the underwater gear to slippery for growth to attach. The problem is that if the boat sits for a while it will attach. Since my boating slows after Labor Day I always have some growth that needs to be power washed off so I am thinking about swapping out this year to try something else.

-Kevin
 
There has been a week at a time that I didn't use it. It was mostly on the weekends and sometimes not even that with rain. Still looks great.
 
I use Pettit Prop Coat. I used it last year and they came off spotless. I do travel a lot also.

Did you ever try the Rustoleum Cold Gavanizing Paint that seem to be talked about alot for this use. Seems like boaters down south use it and compliment it. It makes sense since it has a high zinc content like the Prop Coat.

-Kevin
 
Did you ever try the Rustoleum Cold Gavanizing Paint that seem to be talked about alot for this use. Seems like boaters down south use it and compliment it. It makes sense since it has a high zinc content like the Prop Coat.

-Kevin
Nope...havent
 
I’m interested to hear about this. I think I remember reading here or some other forum that the Rustoleum Product is the same as the Pettit Prop Coat Made by the same parent company in different packaging. Not sure if that’s true or not.
 
I've used Pettit Prop Coat in the past and this year I tried the Rustolium Product. I got the same great results - no growth. sorry about the thread hijack...
 
Well it's spring. I just went for my first run. I'm a little confused on my results. SO he kept the same pitch and added .125 more cup, so now I have .250 cup. It felt responsive out of the hole. Min plane speed dropped to around 17-18 mph. I was able to cruise at 27mph at 3300rpm= .93gph. 30mph at 3500 still= .89gph so my 1gph didn't happen. Top speed dropped to 38.5 mph!! NOW... Thats down by 3mph?? The water was dead calm. I know I have more speed in a little chop. The fuel is 7+ months old. Yes I put stabil in it. I only did 1 WOT run. My WOT is right at 4600. I have 2 full tanks and water tank with 3 people.
 

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