Repower or not ?

[NMG]

I agree with the others. 5,100 RPM suggests to me that your engine is either too low, you need a different prop or both. What RPM's are you running lightly loaded?

The 130 is not known to be a super fast engine, but I'll bet that you get better performance if you can get the RPM's up where they should be (up near 6,000 at WOT). I'd experiment with engine height and props before considering a re-power. It could be MUCH cheaper and leave you quite satisfied.

[4JawChuck]

You will need at least 200HP to achieve your goals, cruising at speeds of 35-40mph will give you better fuel economy than what your getting at WOT now.

Of course how much power you can hang on the transom will be the determining factor.

[fishmonkey]

Is there any Yar craft owners who have a 1785 SC with a 150 on if so what kind of performance do you get ??

[fshrman-r72]

If I liked the boat I would repower with what it was rated for and not a single horse less. Yarcraft is heavy, if that boat is what you like and good and solid check price on re power and make your decision then.

[MERCONLY]

Seriously, Id get the boat set up properly, I work in the Marine business, 95% of all boats are not set up right, you have to prop it to run at the Top of its Rev range with YOUR normal load, full of gas, gear, people etc....also, Stainless steel is the right material for your prop, get a Nice Merc Trophy or 4 blade with your Honda hub in it, but first lets set her up right as is, then we can reprop.....If you need help call me at 847-450-4011 Brannon

[turtle chain]

Originally Posted by BWorner

Seriously, Id get the boat set up properly, I work in the Marine business, 95% of all boats are not set up right, you have to prop it to run at the Top of its Rev range with YOUR normal load, full of gas, gear, people etc....also, Stainless steel is the right material for your prop, get a Nice Merc Trophy or 4 blade with your Honda hub in it, but first lets set her up right as is, then we can reprop.....If you need help call me at 847-450-4011 Brannon

You are so right that is why it is important to buy from a quality dealer that knows what they sell! these dealers that are trying to make a quick $$ that dont know crap about what they sell bug me

[REW]

Fish,
What prop do you have on the boat right now.
As others have said, prop the motor so that wide open you are turning 6000 rpm with the load that you want to carry. You will have to go down in pitch from where you are right now, likely 4 inches in pitch.

Before buying a new motor, at least try a different test prop first.

Also, make sure that you have your motor mounted as high as possible and still keep the prop in the motor and not venting.

If you look at the bottom of your hull and run a straight edge straight back from the underside of the hull, you might find that a good place to start would be with the cavitation plate sitting at a height that is 4 inches higher than the bottom of the hull.

You may or may not get cavitation with that motor height, but that is where I would start.

I think your boat is about an 1800 lb boat and your motor with the right prop should have the boat moving in the 45 plus range. I doubt that you will hit fifty, but you should be in the mid to upper 40s.

If, after you raise your motor, if the motor is too low, you still find that you can't get to 6000 rpm with a reasonable load, then start pitching down on your prop.

You might think that it is counterproductive to go down in pitch to go faster, but if you are lugging your motor, as you apparently are - the use of a lower pitch prop could easily increase your rpm.

Since your main consideration - at this time is speed, I would look only at 3 blade propellers. No 4 or 5 blade props please.

You might get a better hole shot or mid range with a 4 or 5 blade prop - but the 3 blade prop will get you the most speed if it is the right prop.

-------------
If you want to go larger, certainly the use of the 150 - Yamaha, or Suzuki 4 stroke would both be excellent choices.

My buddy has a 20 pitch Yamaha stainless on his 150 prop on a boat that is comparable to yours. With the two of us on board, and on a decent day, he will be running about 50-52 mph. In the high heat and humidity of summer, that number will be about 48.

Summer heat and humidity normally takes 3-5 mph off the top speed of any boat. This is directly due to the power loss of all motors caused by the different air density and the water content in the air being ingested by the engine.

Now, take a cold Oct day when the temps are 36 degrees, that speed might very well be 55 mph, with the very cold dry air being ingested by the engine.

An outboard engine is nothing more than an air pump that uses fuel to run the pump. The more air that it can pump, the faster it can go. The drier and denser the air, the more oxygen it contains and the faster the engine runs.

So, try motor height. If that doesn't do it, then try a different prop, at different motor heights if necessary.

If those things don't help, then drop the $12k for a new 150 4 stroke and the right stainless prop and you will be good to go.

REW

[REW]

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[ffishman]

If you do make the switch, and spend the big bucks, probably around 15k, ask yourself. Is this worth the money, and how long are you planning on keeping the boat. You will have to keep it a very long time to get your money outof it. Just think, if you try to sell it in a year, you will be trying to sell an 11 year old boat with a 1 year old engine. Would you want to spend bucks on a boat like that. Probably not. You will never get your money out of it. Best bet is to sell or trade yours and get the boat you want.

My brother has the same boat as yoy, but with a 115 honda. When he bought it, it was a complete dog. After repropping and putting an edge hydrophoil on the boat he can run 42mph. He still has a few more rpms to get to that 6000 and may try repropping, raising motor, ect... REW's post sounded dead on, I would try to set up what you currently have before repowering. If then you are not satisfied, price it out and then decide. One thing to remember, yarcraft no longer makes the 1785sc, that is one sweet fishing boat! Another comment is I recently bought a 1785dc with a 135 opti on it. I repropped from a 21p lazerII to a 19p temest and gained 3mph. I still could use a few more RPM, but it has been hot and humid and as REW said this may make a difference. My top end fully loaded with a kicker, two poeple, gas ect... is only 43MPH. These are heavy boats but ride great. I had a 1785bt prior to this and it would run 33 with a 75 two stroke merc, but weighed way less.