New to this

[Palomba]

I purchased a 1993 mirage trovare 257. 26ft bow rider with a 7.4 Mercruiser. Got it tuned up and running good. Engine and boat seem to be in great shape. I’m new to the boating scene as an owner and have a few issues or questions. Boat holds 82 gallons of fuel and is rather on the heavy side for a play around boat. With half a tank of fuel and 3 people the boat did 58-60mph at about 4500rpm. But it does not like to cruise much less than 4000rpm. Your either doing 40 plus or 10mph no matter how I trim it. Took it this weekend with 8 people and some coolers and could barley do 25-30 wide open with a full tank. After we burned some fuel it would do about 45 on semi rough water, but at 4100-4200rpm. It’s slow to get up and get moving. It has a mirage prop on it now but unsure if the pitch. What should I be looking for? 2 props for being loaded with people and wanting to pull a tube and one for a few people and running around? We tried to pull the tube and ski and it was slow going. Did not like dragging the tube much past 20mph with 5 people on board and 3/4 tank. The way it runs with just a couple people at over the desired rpm wide open makes me skeptical of switching props. It will generally have 6 people on board and be pulling a tube. Hard to find much info on this boat. Thanks for the help. Sorry for the dumb questions!

 

[alldodge]

The boat specs show up as 375hp so should be a EFI/MPI and B3 drive. The boat is not that heavy at 4000 pounds, my Rinker weight is 3800 and I have a 300hp carb with B1 drive and will do 60mph

http://www.mirageboats.com/specs/257br.htm

What is the engine serial number?
What drive do you have?

Your WOT rpm is a bit low and should be around 4600-5000 IF this is a EFI
One thing you can do to help is don't fill the tank up. Don't know where you boat or how much fuel you burn during a day, but I never fill my tank unless need be for a very long trip.

 

[Starcraft5834]

@ 26 ft that's a big boat.. 4 blade prop would give you more bite, get on plan faster and stay there at slower speeds than your 3 blade.. you may lose a mph or two top end speed with the 4 blade... if your going to host a boat load of people and perhaps tube or ski too.. 4 blade will be better choice for that situation. usually drop down (1) in pitch on the 4 blade.... regards..........

 

[porscheguy]

If you’ve got a mirage prop, the pitch should be stamped on it. A mirage is an ideal prop for a boat your size, weight, power.

It does sound a bit like you’re overpropped however. That means your pitch seems a bit high.

To locate your pitch, look on the prop for a part number. After the part number you should see a 2 digit number with a “p” suffix. (I.e. 19P, 21P, 23P, etc). That number is your pitch.

A lot of boats like yours tend to be propped to run at high speed at the cost of acceleration.

It’s not uncommon to have more than one prop as it only takes a few minutes to change them to optimize the boat for the day’s activities.

Find your prop pitch and let us know.

 

[Palomba]

Boat is a carbureated 7.4 with thunderbolt ignition. I will get the specs of the engine and outdrive asap and let yall know.

 

[QBhoy]

Lots going on in terms of variables here. Really hard one to get spot on.
Just a couple of points.
I don’t think this will be a bravo 3 of it has a mirage single prop maybe although knowing aldodge, he is unlikely and rarely wrong with these things

80 odd gallons of fuel is a hell of a weight to carry around. It’s over 300kgs or well over a quarter of a ton sitting at the back of the boat. Have a think about that haha. It’s like carrying a modern big 3 seater Yamaha cruiser spec jet ski on the back of your boat or an extra 4/5 people, depending on how well fed, haha.

Your rpms at your best speed at a suggested near 60 mph are quite low compared to what I might imagine perhaps. Lower rpm might suggest you are over propped likely.

Hard tk get it right if you have vastly varied usage in terms of weight on board etc. If you are usually well weighed down with fuel and passengers you will see a huge detriment to performance compared to lightly loaded. My own boat can drop over 10 mph with just a couple more people on it and the canvas hood up.

Just need to either have a few props for different uses or give in and find a good all rounder. Not usually done in one go to be fair.

My boat is a rocket ship with a higher pitch enertia, ballistic or even laser 2 prop. But put a few people on it, have the hood canvas up or god forbid want to ski off it....and all the props above are useless. I know have a 2” lower pitch laser 2 on it. Cruises well, accelerates well enough. Droppped about 3/4mph but performs better generally. Always a compromise

 

[Palomba]

I will get the specs this weekend. I keep In indoors about 30 mins away just hard to go that direction during the week. Max rpm shows 4200-4600 if I remember right. O was worried to push it past that, older 454 not sure how bullet proof they are. It drinks some fuel I know that. I had to build a new trailer and such since I got it a few weeks ago. Have had it out 3 times. First time it wanted to misfire at times and spit and sputter. Had a lot of corrosion in the distributor cap. Did a full tune up and new coil and water separator and that was cured second time out. This last time it was really loaded down and kinda disappointed me. I will get all the specs and report back! Sometimes it acts like it wants to cavitate. It don’t like to trim up to high. If you go to high it’s like your in neutral and revs our to 5k have to back out of it and get back in it to get going again. So was just thinking maybe it’s over propped. But with running 60 being 26 foot long I figured that was more than impressive. No blow by or anything with the engine. Clean clean clean oil and great oil pressure. Starts as soon as you bump the key. But I bought it to get out with friends. Drink some cold beer and throw each other off the tube. And it don’t like the weight when loaded. Made me nervous being all the way in it and barley running 30 with a full tank. But granted the water was far from calm.

 

[Palomba]

Ok so got out again this weekend. At 4400 rpm with 5 people and the normal safety gear. And about half a tank of fuel (40 gallons) boat ran wide open trimmed up at 44 mph and 4400 rpm. My max WOT says 4200-4500 so I’m within that range. But just me headed to load up it does over 50. Prop is a quicksilver mirage 23p. Am I getting bad prop slip? The weird rpm range being about the same but going faster with less weight throws me off. Loaded heavy it’s a dog. I’d like to have more umph pulling a tube or skier. But want to keep some sort of top speed.

 

[WesNewell]

Until someone provides a 2 speed drive train where you can use the same prop for both power and speed, you will just have to change props for the conditions you want. if you want more pulling power then get a 20p prop to use when you want it.

 

[alldodge]

Agree with Wes, and don't know what ratio drive you have, but if its 1.5 then you slip is up to 31%. You could go to a 21 pitch and have the prop cupped to increase bite (something like 22 pitch) and this would help on hole shot, but your you can over rev.

Changing to a Bravo 3 lower will also increase bite, but you may just have a tired motor. Do a compression test and check plugs for color