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  1. #1

    Default what's the best way to get my boat to plane out?

    I actually have two issues and they may be related.

    I have a 2003 Mariah SC21 with a 4.3MPI merc. So, it has 220HP, which should be enough to get this boat out of the water. If I have four adults and one teenager in the cockpit .... the boat WILL NOT plane. I could go across the wholes lake with the bow in the air and it just will not plane out. If I have someone run up in the front of the cabin as a ballast the boat will finally plane.

    I saw in my owners manual that the Alpha outdrive has a spacer that can come out to give you another 1 1/2 degrees of trim-in. I think this would do the trick and I would obviously trim it back out when I got under way. The boat is plenty fast once on plane so I usually have neutral trim position, unless the lake is really bad. I have a feeling if I ask my marina to take those spacers out, they're going to look at me like I have three heads.

    I am assuming trim tabs are pretty expensive, so that's probably out of the question.. (the financial committee would not approve)

    I have also seen those "wings" you can put on your lower unit. Anyone know how much those should cost and how much they would help my situation ?

    The other issue I am having is that I'm using WAY too much fuel. It is injected so I had hoped to get better "mileage" from it. I put thirty bucks in at the Weirs docks and was empty again when I got to Alton bay..(which is about a fifteen minute ride)

    My last boat was a bow rider that could plane out no problem and would go for a couple days on 30 bucks...(and gas was more expensive last year)
    I know this one is heavier and it is a cuddy cabin, but
    is this boat that much of a gas hog or is there maybe something wrong?

    thanks for the help....

  2. #2
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    Default Re: what's the best way to get my boat to plane out?

    you should be able to get smart tabs on this site for a hundred or so dollars i will be getting mine soon i believe from all the posts that they are the bomb definitely would not go with the hydrofoil=as far as the gas mileage-you should not dump 12 to 15 gallons in 15 minutes--look for leak--if it was overfueling then you should have smoking and driveability problems--also make me concerned that you may have soaked foam if heavy in rear and sucking gas--have boat weighed

  3. #3

    Default Re: what's the best way to get my boat to plane out?

    It did smoke a bit the first time I started it (just bought it last week) and a couple people in the back have complained of exhaust smell. This soaked foam thing sounds very very bad.... where would I go to get it weighed ?

    Thanks again...

  4. #4
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    Default Re: what's the best way to get my boat to plane out?

    local trash dump--trucking company--dmv --etc

  5. #5
    Lieutenant Junior Grade Thad's Avatar
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    Default Re: what's the best way to get my boat to plane out?

    I think you may have a few issues to deal with here.
    The first thing is definately get her weighed. When you do, have all of your gear OUT, and have a full tank of fuel. That way, you can deduct the weight of the fuel from the total. You will also need to know the weight of your trailer. If you can't find it, weigh the trailer without the boat so you have a tare. Compare your net weight against the actual. If you do not have it, NADA gives dry weight.

    Another issue, that may be combined, is the fuel useage and planning. If there are problems with the engine it can account for both. As well as if you are water logged.

    Personally, I have never liked the idea of a V-6 in anything bigger than a 19 footer. They do produce the hp, but not the torque.
    You may only need to get a different prop and not actually have any problems at all.

    Someone with a lot more knowledge than me will surely chime in on this one.

    I'll be watching to see how this turns out for ya.
    Livin' the Dream...Chasing Life

  6. #6
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    Default Re: what's the best way to get my boat to plane out?

    You shouldnt have to remove the spacer from your drive, you have other issues.
    Does your boat reach the recommended WOT range?

  7. #7
    Petty Officer 2nd Class AngelC's Avatar
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    Talking Re: what's the best way to get my boat to plane out?

    Your probably under propped and bogging out the engine, therefore burning excess fuel at full throttle..
    Angel

    2007 Larson Senza 206 5.0GL I/O Volvo Penta 220hp
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  8. #8
    Moderator aspeck's Avatar
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    Default Re: what's the best way to get my boat to plane out?

    Check your rpm's at WOT (wide open throttle) with the engine specs. You can find them online. Make sure you are in the accepted range (prefered higher end). If not, downsize the pitch of your prop. If you are, then start looking for engine and weight problems.
    Rules of Repair:
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    3. If you can't fix it with a hammer, you've got an electrical problem.


  9. #9
    Moderator QC's Avatar
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    Default Re: what's the best way to get my boat to plane out?

    First off, welcome aboard!! While this appears to be an engine issue with the possibility of the soaked foam contributing, I think this probably belongs over in the I/O forum. Let's try narrowing this down as there may actually be three things (or more) needing attention:

    1) Weight

    2) Prop

    3) Engine condition

    Quote Originally Posted by bimini crickets View Post
    I have a 2003 Mariah SC21 with a 4.3MPI merc. So, it has 220HP, which should be enough to get this boat out of the water.
    Yes, but it will not be a rocket ship. Many guys are running 320 hp in this size boat.

    Quote Originally Posted by bimini crickets View Post
    I am assuming trim tabs are pretty expensive
    With your power and boat combo, when this thing is right they would be a great addition. Need to get her as right as possible first, but tabs are an amazing tool.

    Quote Originally Posted by bimini crickets View Post
    I have also seen those "wings" you can put on your lower unit. Anyone know how much those should cost and how much they would help my situation ?
    Forget that!!

    Quote Originally Posted by bimini crickets View Post
    The other issue I am having is that I'm using WAY too much fuel . . . I put thirty bucks in . . . (which is about a fifteen minute ride)

    My last boat was a bow rider that could plane out no problem and would go for a couple days on 30 bucks...
    While this appears to be very excessive, let's get these numbers in Gallons as we don't know your fuel cost. Also the only way to confirm usage without a fuel flow meter is to fill her and then refill. We cannot base anything on a fuel gauge . . . Way too inaccurate.

    Last, we MUST have correct WOT RPM data. Go down to the Prop Forum and read up on what we need. The performance issues (including fuel and even the smell) could be 100% propeller. Also, what altitude?

    Good luck, we'll help you get her right, but we must have info, lots of it and accurate . . .

  10. #10
    Petty Officer 1st Class Tahoe 55's Avatar
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    Default Re: what's the best way to get my boat to plane out?

    If all else is right (mechanically and prop pitch), Smart Tabs would be the answer. 100$ is pretty fair for what they do....
    2007 Tahoe Q8i Sport Blue
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  11. #11
    Supreme Mariner Silvertip's Avatar
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    Default Re: what's the best way to get my boat to plane out?

    You cannot pour 15 gallons of fuel through a 4.3 in 15 minutes. Step 1) Make sure the engine is developing full power. This requires that you ensure the choke is working properly. Then engine mechanical condition is ok (as in a cylinder leakdown test, or at least a compression test). Pull the plugs and check them. If you don't know how to "read" a spark plug do an on-line search. Step 2) Check the prop diameter and pitch (either stamped on the barrel of the prop or on the hub behind the washer.) Step 3) As suggested, check for water soaked foam.

  12. #12
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    Default Re: what's the best way to get my boat to plane out?

    Smart Tabs would be the answer

    I have serious doubts that tabs wouldn't be just an upgrade. That boat should plane out with the equipment it has. Something else is wrong. I run a 23.5 footer with an engine rated at 240HP. Had 6 people in her yesterday on Lake Erie and never had a problem getting her up on plane. I don't have tabs either.


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  13. #13

    Default Re: what's the best way to get my boat to plane out?

    lot's of good places to look... thanks to everyone who chimed in..

    I don't know my WOT rpm because my tach is all over the place (check my post in the electrical section) because I also have an issue with the radio shutting off if I trim up or throw the dock lights on, most people told me to clean the terminals and connections, which I did very thoroughly..did not help, it may just be time to replace the battery.

    So I changed my plugs today and the ones coming out actually looked pretty good.

    I check the spark arrestor/filter and it was clean.

    I went out with just me and one friend and the boat planes out in about two or three seconds, which is what I would expect.

    we were thinking about it today and the day I had four adults and one teenager in the cockpit (and no one in the cabin) we had between 1,100 and 1,200 pounds of people with us that day, and the weight is really far back on this boat. so maybe I don't have a problem at all (except that I hang out with overweight people ????)

    By the way, thirty bucks will only get you 10 or less gallons around here, it hardly ever goes below $3.00 / gallon on the lake (which is where I fill because we are on a slip on Lake Winnipesaukee.but that still seems excessive since I was alone that day (but I did head back most of the way at WOT) so maybe I need to keep it at 3/4 or so...?

    and I have no idea what the altitude is here.... (Laconia, New Hampshire)

    seems pretty unanimous on the smart tabs though, I'll have to get a set of those...

    I want to thank everyone who chimed in again , and if you have anything else to add, feel free.....

    I wonder if it planes out with just a couple people in the cockpit, maybe my foam isn't soaked ..(hoping)... it did make sense when I read it though because the back end moves around a lot at slow speed....like trying to steer a bath tub, but I have been told that it is a characteristic of that boat....I have learned to control it and start my turn in early at the dock and let my back end come around like it wants to..

  14. #14
    Rear Admiral Maclin's Avatar
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    Default Re: what's the best way to get my boat to plane out?

    You really should verify the top rpm's with a "shop" tachometer, usually dwell meters and even fancier timing guns have a tach feature. Knowing the WOT rpm's with a light load along with knowing the actual prop pitch number will give some good ides on what direction to take if anything actually needs to be done.

    If the WOT rpm's seem correct and the spark plugs read normal (not too rich and not too lean) then you may be done troubleshooting. In my opinion IF you do not normally run with that many people AND you can move people to the bow and it can plane out in 5-7 seconds then you may just need to get used to that when "over" loaded.

    My advice centers around the prop pitch and the way you use the boat. The 4.3, even in the 220hp configuration, will not have as much grunt down low like a 5.7 or even a 5.0. I have a 21.5 foot cuddy with a 275hp 5.7 and I run a slightly lower pitch propset than the engine really demands but we are almost always towing and have a lot of people and coolers in the boat. It comes out of the hole great this way in every situation. I sacrifice some top speed maybe but it can still go above 45mph at 4,600rpm or so any time we need it to even loaded like that.

    If you do decide to go down in prop pitch (and do not decide ANYTHING until you know the prop pitch and the WOT rpm's) for more low end power then you will have to watch the rpm's as that particular engine gets rev-happy above 4,000rpm. It may have trouble getting out of the hole but once it does the power band is up high and she can run away from you quickly once it gets on plane.

    The Marias I looked at of that vintage had hull extensions that went past the transom a foot or so and that should aid in planing and handling. If your hull's design has those then I am leaning towards on under-powered/over-propped situation you are "inducing". I am also mentioning those because it makes for a challenging SmartTabs install.

    While weighing it is just a good idea anyway, it seems like flotation foam is only required in boats under 20' so waterlogged foam is probably not an issue, (and I said probably!).
    "TaylorConn", our 1991 HydroSwift 2200 Cuddy Volvo Penta 570/DP

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  15. #15
    Rear Admiral Maclin's Avatar
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    Default Re: what's the best way to get my boat to plane out?

    And regarding...:"it did make sense when I read it though because the back end moves around a lot at slow speed....like trying to steer a bath tub, but I have been told that it is a characteristic of that boat....I have learned to control it and start my turn in early at the dock and let my back end come around like it wants to.."


    Tha is typical of an I/O and called slow speed wander, definitely not unique to your boat!

  16. #16

    Default Re: what's the best way to get my boat to plane out?

    That all makes a lot of sense,

    just as an update, I went out yesterday with a total of two adults and three kids and the boat planed in less than two seconds.. it jumps out of the water in that scenario.... and you are absolutely right about it taking off when planing..it's like your turbo spooling up and you can definitely tell when it planes.

    I am happy with the boat overall, I guess I just need to get used to it.

    It's not my first boat, but I have always had bowriders which had very little wander and a more even weight distribution, so even my old Glastron with the 3.0 came right out of the water, even when "freighted"

    This is my first cuddy and it acts TOTALLY different than any of my bowriders.

    I think the boat is dialed in pretty good. I also noticed a much better fuel consumption yesterday because I wasn't running across the lake WOT (had the kids with me, ya know...) that motor is definitely "rev happy" like you had mentioned..

    now if I can just figure out if I actually need to spend $100 for a new battery, I'll be a happy camper..(errr boater)

    I really want to thank everyone who chimed in on this thread, I really appreciate the help !!!

  17. #17
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    Default Re: what's the best way to get my boat to plane out?

    A new to you boat with a battery you know nothing about out on the water away from jump or charger, ah yea a new or spare/auxiallary battery is probably a good idea.
    Fix that tune/trim/light wiring problem too, sounds like a nice boat.
    Planing is hard with all the weight in the back, that 4.3 is back there too.
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