Humidity

[EJP]

I have lost 5mph or so with the onset of summer, is this normal. I do live in MD and we have alot of high humidity days.... is this the cause??

This is my setup right now... I am 1/4" below running around 13psi at wot... I have put the propshaft at even and had 11psi, but by myself I could only get 76mph and 5700max rpms with horible blow out. At 1/4" below I have hit 81.2mph by myself. I am spinning the 27T1 to a maximum of 5900rpms (can't get anymore)... recommendations...

[chad202]

Heat and Humidity are big time HP killers. If all conditions are right, on any given day, you could be down as much at 10-12% HP. 225X12%=27. Now your 225 is only a 198HP motor. I normally loose 3-4mph.

[EJP]

I have been experimenting with this alot latley... if it is high humidity I loose about 5 mph compared to my chillier weather numbers..... crazy!

[Lea]

Not crazy...just facts of life. While no speed demon, I got 71.9 with my Champ/225 Opti combo on one of the hottest days of the year.... With cooler. less humid weather, and a prop change, I more than likely would have done 74-75....

I don't tournament fish, so would not have worried about beating anyone to "my spots".....but I am definitely good with what I get...

[Blazenzeek]

I wouldn't be overly concerned. Your like me...you fish more than you care about going fast. You will loose some performance w/ the onset of the dog days but I will say my Yammi is much less sesnsitive to this than the Mercs I used to run. I'm guessing it is because of the larger displacement.

So much effects speed...water condition, heat, humidity, weight, weight distribution, etc. With out knowing more about the other variables, its a guess to say if the weather is driving some, most, or all of your speed loss.

If its really bothering you, take a day just to play with set-up. Go out with just you and a moderate load. Start early before the heat / humidity get way up. Try to catch a day w/ some chop on the water. Try to balance the load as much as possible and get as much to rear as you can. Don't go to extremes...just play with it so what differences it makes.

I have found that most of my speed drop-offs are a direct result of all the crap I put in my boat. Once I get the 8000 lbs of plastic and the tools/ spare parts required to build the boat 3 times OUT of the boat, it runs like it is supposed to. You should have no problem seeing low 80s with you and a moderatly distributed load on a morning w/ moderate temperatures and a light chop.

Play w/ the plate as needed just make sure when your done w/ set-up that you make a run w/ all the junk back in, livewells full, and your fat partner sitting beside you just to make sure you won't have any performance issues (blow-out, psi, rpms, nose falling) with all that back in.

Keep an eye on those plugs. The manual says change every 50 hours. I put a new set in at 10 after break-in and at exactly 40 hours later, I fouled several...and when they started going, top end was the first area effected.

Doesn't sound like that is your issue because once they start to go, they go quick...but something to keep in mind never the less.

[EJP]

No I know it is the humidity Zeek.

For instance two sundays ago I fished a small club tx. It was me and another guy about my size (175 or so), and he brought a fairly large bag of tackle, as well as my fairly large collection. It was raining off and on but I would say 100% humitdity, and 85 degree air temparture. I only got about 75-76 I forget exact.....

This Saturday, same load different guy. We had 85 degree air, 15% humidity, and light variable winds, 78mph..... I am happy with 2 people fully laoded 78mph, thats freaking fast......

I am just commenting how much of a difference I loose in extreme humidity. It's also a shame I live in Mid-atlantic where high humidity (80-90%) are very very common....

The way I look at it is, my boat went almost 82 with just me and my normal load in the spring the way I have it set up now.... Thats fast no matter which way you look at it, sounds to be setup just the way it needs to be to me!!

I do however wish I could squeeze the last few 4-5 mph f they are there, but I'm not really sweating it.... I would say the average water quality where I fish (Potomac River mostly) is 1' or more constant wakes, so you don't get to open up that much anyways.

[Blazenzeek]

Optimal set-up changes w/ load. What was best for you by yourself and a "normal" load will not be the best set-up for two / heavy. That's why my next boat will have a hydrolic plate. Without it, you always have to compromise. If set-up for one, you will not be for the other.

[Porkfrog]

Chad, you mean to tell me that if i'm running a 300hpdi in this H/H that i'm gonna loose 36hp? and 4to5mph! that's hard to beleave it's that much!!!!!

[chad202]

The newer tech motors are not as bad since they all these fancy sensors. If you get B&W, they did a full article on how much heat, humidity, and barametric pressure affects HP output of a motor.

[WDBrand]

EJP...........Humidity, water and air temp. rob HP. Here in florida where the humidity is terrible I typically go down 1 inch in prop pitch to turn more rpms and also get a little better prop efficiency to make up some of the difference. As a rule of thumb every 10 HP = 1 MPH speed. JMHO

[1fstblazer]

Believe it ! All the guys down here in Tuscaloosa, Al have the same problem. But remember everyone else is also I will drop from 80 to78 with high humidity 2 people full tanks full live wells full tackle for both people and run 82 in the winter with the same load.

[LookOutForShoals]

I remember in my drag racing days how much Trap speed I would lose on a hot and humid night. I think its usually more the heat than the humidity. If you do the chemistry, you just can't burn as much fuel with warm air as cool air.

Oh yeah EJP if you really wanna slow that boat down, I will come and go fishing with you, and I will show you how to slow that boat down, hahahaha.

[nsteere]

My friend has the stage 3 Hydro tec in his 300hpdi. He is down 5mph this summer. He usually turns a 31p, but has to go to a 29p for hole shot and to get max RPMS. Worked engines seem to take a bigger loss in the heat. He has seen 90+ in the winter and lucky to get 85mph in the heat. So yes I believe these engines lose 30+ hp in the summer.

[spider1]

I don't loose any cause I don't run when it is cold!!! All my runs are 80deg and above!!!

[blazerman]

not another fair weather fisherman

[Fear-This]

It drop to 80 in NC on Sat day took the boat out she ran 79 gps with full load and partner no fish week before 96 she ran best 76 gps hmmm heat robs power

[spider1]

Not fair weather so much is just not in the cold!!!!
The old bones just can not handle it like they use to!!!

[chad202]

Spider, you just need to bring some drinks that keep the inside warm.

[spider1]

Chad, boat is to fast for that kind of warming of the insides!

[chad202]

I hear ya Spider.