Too Much Prop? Help Please

[Nitro_boy]

I have an 18.5 foot nitro savage 884 Bass Boat with 150 hp merc EFI I can't get on plane with half a tank of gas for like 15 seconds. The prop is a Stainless 4 blade. Trophy 48825940 24p. I had the motor serviced recently and it is running ok on plane but no holeshot. It runs good almost empty but with gas in it bogs down a ton. The boat tops out at 5500 rpm.Also the three vent holes measured 5\16 of an inch. Thanks guys.
Aaron

 

[hwsiii]

Re: Too Much Prop? Help Please

Nitro, if you could tell me the year and model of the engine so I can get the gear ratio that would be helpful, as well as the speed it is attaining at 5,500 RPM with the weight of the boat and how much fuel you carry, I can give you some better numbers.

H

 

[Nitro_boy]

Re: Too Much Prop? Help Please

it is a 97 efi as for the speed the speedo says 50 to 55 I don't have a gps. The tank holds 27 gallons and I had three quarters of a tank and all three batteries as well as two of us 250 lb guys. I think I need smaller pitch I just need to be pointed in the right direction.

 

[Dhadley]

Re: Too Much Prop? Help Please

A Trophy wouldn't be my first choice for that boat but let's work with what you have before spending $$ on another prop.

Do you have a jackplate? If so, have you tried going higher?

 

[Nitro_boy]

Re: Too Much Prop? Help Please

There isn't a jackplate on the boat. On a windy day like today I had to have my partner get in front to get on plane at all. I'll put an aluminum prop on it if I have to. I only fish small lakes.

 

[hwsiii]

Re: Too Much Prop? Help Please

Nitro, the trophy is definitely the wrong prop for your application, as it has way too much rake and that is causing the tremendous bow lift you are experiencing and why your partner has to sit in the front to get the bow down. I don't know how many of the vent holes you have open or closed, but you are definitely experiencing too much bow lift, and if you are using a 24" pitch you have too much pitch as well, which tends to also make the hole shot and acceleration slow.

H

 

[Nitro_boy]

Re: Too Much Prop? Help Please

That explains alot. What kind of numbers should I look at? I have a local Merc mechanic and he has some different used props there. Maybe I could find someone to trade with. All three vent holes are open at 5/16 Thanks for your help.

 

[hwsiii]

Re: Too Much Prop? Help Please

Nitro, lets hear what Dhadley has in mind first, because I can tell he has some suggestions from his post, and maybe he knows more than I do about how to fix your problem at a much cheaper price. I am always willing to gain more knowledge and he just may be more knowledgeable than I am on the trophy props. I would hate to give you an expensive fix when he may have a much cheaper one. Do me a favor though and check the Diameter and Pitch one more time off the prop and give me those numbers.

H

 

[Tail_Gunner]

Re: Too Much Prop? Help Please

Nitro, lets hear what Dhadley has in mind first, because I can tell he has some suggestions from his post, and maybe he knows more than I do about how to fix your problem at a much cheaper price. I am always willing to gain more knowledge and he just may be more knowledgeable than I am on the trophy props. I would hate to give you an expensive fix when he may have a much cheaper one. Do me a favor though and check the Diameter and Pitch one more time off the prop and give me those numbers.

H

Agreed there ...when Dhadley is giving advice, place close attention the rest of us are a peanut gallery...no exception's...

 

[Nitro_boy]

prop help

prop help

Ok pro's I need a prop suggestion then for my boat. Can I get some help here? Probably aluminum due to price.

 

[Varago]

Re: Too Much Prop? Help Please

Something to think about

What merc has to say about that prop

"Small exhaust tube allows increased venting for V-6 outboards (if over-venting occurs try 878421 seal ring)"

the hub is smaller then std to let more exhaust gases past the outside of the hub but to much and your hole shot is gone.

Dave

 

[Dhadley]

Re: Too Much Prop? Help Please

The Trophy really needs to be run higher. As a general rule of thumb it's better suited for boats with jackplates and/or a high X dimension. Those boats really respond well to props like a Turbo Lightning but again they're meant to run higher. An aluminum prop will work OK but won't have the performance of a stainless. Try to get as much tip cup and rake as possible. You might even think about looking for a 3 blade Stiletto.

 

[hwsiii]

Re: Too Much Prop? Help Please

Nitro, are all the vent holes closed.

H

 

[Nitro_boy]

Re: Too Much Prop? Help Please

The vents have rubber type rings but openings 5/16 of an inch on all three.

 

[Nitro_boy]

Re: Too Much Prop? Help Please

I just ordered the seal to try it and see if it helps. What are my chances guys? I'd rather try that than buy an aluminum one. I talked to my Merc guy and he said a 22 in stainless would be better or 23 in aluminum due to me topping out at 5200 wot with the trim up.

 

[hwsiii]

Re: Too Much Prop? Help Please

I totally agree, I think you are getting BLOWOUT. And that is a CHEAP fix.

H

 

[Nitro_boy]

Re: Too Much Prop? Help Please

Will that seal fix the blowout? Thanks for your help

 

[hwsiii]

Re: Too Much Prop? Help Please

Nitro, I don't know that it will totally cure it, but it will certainly help the blow by which ought to help a bunch. Nitro you might try to install a small nut and bolt with one washer on each side of the prop on each vent if you have nothing else to fill the vents with at this time.

H

 

[Nitro_boy]

Re: Too Much Prop? Help Please

When I pull the prop to install the ring I will put bolts in all three exhaust holes. Would it be better to epoxy them closed instead?

 

[Varago]

Re: Too Much Prop? Help Please

You can get the PVS vents from Merc or some of the marine dealers, they are cheap about 5$ for a bag of 5. They come in 3 hole sizes or no hole at all, so you can tune the vent to your boats needs.


Dave