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Posts: 51
| I like the Boat a lot (may be a little over powered).
With a 150 HP Yamaha 4 stroke and a 8 HP Yamaha 4 stroke kicker I'm wondering if it has a little to much weight back there, but not much can be done with that.
Have tried moving starting battery to front but even with 6 ga. wire didn't work.
Everything about the rig is fine with one exception I'm looking for opinions on.
When taking off (or slowing down speeds) the bow is uncomfortably high to the point it is a difficult to see ahead, and can be bothersome in rough water. Is perfectly fine underway and "trolling speeds".
Has an SS prop 19 11 (actually looks like 19 M).
Straight line from bottom of cavitation plate to bottom of the of hull measures about 1/4" - 3/8" higher than bottom of V of the hull which appears to be about right.
Motor is now mounted in second hole from the top of mounting plate (3/4" distance between holes with two more down down.
Any thoughts on raising the motor or even different prop?
Any advice is appreciated.
The Rad Dog guy.
Mike |
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Posts: 676
Location: Wisconsin | Might be worth a shot to try a 17" pitch prop and see if that helps on hole shot? I have the same boat minus kicker with a 130 etec and I have a 17 and it seems to work very well. Good luck. |
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Posts: 3469
Location: Elk River, Minnesota | Hiya,
The 19 pitch is about right for that rig. What I would be wondering about is what hole the trim-stop pin is in on where the motor mounts to the transom. If that pin can be moved inward (toward the hull) a hole, that can make a huge difference in the way the boat comes out of the hole. Moving it in will allow the motor to "tuck under" a little more, thus forcing the bow down and the rear up.
I'm curious as to what prop exactly you are running. If you can find a nice 19 pitch pro-series prop (yamaha), a tempest (mercury), or even a ballistic (michigan wheel), you might find the trailing edge cupping will allow the boat to trim better and have better stern lift.
That rig should be a great rig!! I have a 165 navigator with a 90 2 stroke and have loved it for years.
Steve
Edited by VMS 5/4/2017 10:10 AM
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Posts: 271
Location: davis,IL | I have a 185 navigator with a 150 yammie and a 5hp merc. Yeah, its tail heavy, and the bow pops up. Just make sure the majority of heavier tackle is forward, as to being overpowered , I don't think so. You should see around 50 mph top speed. The thing to note is your rpm at w.c.t., should be 5600 - 5800. If it is the you are propped correctly, you could also run a 18" 4 blade , a little slower but more control. |
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Posts: 51
| That is pretty much right.
Seldom run wide open but the, yes, about 50 MPH at around 5600-5800 RPM.
There are no holes for nor a trim stop pin. What are your thoughts on raising it up a hole (3/4")?
I found a fin set. Like the dole fin but 1/4" aluminum bent upwards about 1" in front and down about 1 1/2" in the back, it is about 9-10 long, maybe 2-3" wide in front and 8-9" wide at rear, looks like will maybe help with lift.
Have used fins before that didn't seem to help much other than assist in emergencies to use as step to get back into boat.
Thanks again
Mike
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Posts: 390
| I while back we had a crestliner that was very tail heavy and could be downright scary at certain speeds. We added a fin to the lower unit and it help immensely. |
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Posts: 271
Location: davis,IL | It sounds like your propped correctly. As to the fin, that's a hit and miss deal, it may be great or maybe not so much. A 4 blade prop can have a very noticeable change also, but I cannot tell you which prop is the right one. Any of this stuff is an experiment, if your lucky, you'll find the magic bullet quickly. If not.....well it can get expensive (swapping props) and such. I really haven't been overly bothered by the high rising bow because I'm pretty easy throttling up and down. As to raising and lowering the motor, that's an experiment too. But... raising the motor will at some point cause the prop to have less overall lift while running at speed, also less bite in a chop. So try it and see what you get. The key to any of this is when you make a change make sure you run it in its most used configuration. This means if most of the time your fishing alone, then test that way, if most of your time is 2 guys and gear, test that way. Also note how much fuel you have on board....the key to testing changes is keeping everything else as close to same as possible, that way you will get a real feel for how effective any given change performed. |
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Posts: 3469
Location: Elk River, Minnesota | Hiya,
One other thing that can be done, although it sounds ugly to begin with, but you won't notice anything in the end is to have the rear of the hull "wedged."
On my navigator, I found the same thing as you, except for me I could not trim the boat up. As soon as I was at full throttle, I'd start to trim up, and the bow would bounce. I took it back to Alumacraft and met with an engineer there, who immediately ran his hand across the edge where the hull meets the transom. Evidently, the fabricators peened the transom up a touch too much so trimming would not be possible.
So...with that being a possibility to do, all it involves is a simple hammer and a mason's chisel. Working from about 3 inches in from the outside edges, use the hammer and chisel to wedge a little wider opening between the transom and hull. Work your way along for about 18 inches...the main flat portion of the hull. It doesn't take much, but if you open it up...oh..say...1/8" and test, I bet you might find the bow does not come up as much. If the bow is not able to rise with trim, then all you need to do is peen the wedge closed a touch and retest.
If you are in the twin cities area, I'd be willing to meet with you and help out if you'd like.
Once you find the best for your liking, find silicone to match your hull color, silicone the wedged area, and nobody will even be able to tell you did anything to your boat. This helps keep value up as drilling holes in an anti-ventilation plate and installing a fin actually reduces value, and in my humble opinion is only a bandaid fix for a set-up issue. If the boat is properly set up to run as efficiently as possible, the fin is entirely out of the water while on plane. At that point, it is not doing anything. If the motor is flat to the transom, the antiventilation plate is most likely underwater, creating more drag (think of sticking your hand out the window while moving 60mph). Underpowered boats have this issue, and the fin helps the boat plane out due to hydrodynamic design which creates lift in the rear.
I'd say if you are on a good steel prop, coming up 3/4" will give you some more top speed as well...
Steve
Edited by VMS 5/5/2017 9:07 AM
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Location: Eastern Ontario | Steve gave me that same advice for an Alumacraft Magnum I used to own Scary but works |
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Posts: 51
| VMS
Thanks again Steve
There appears to be about 3/16" of hull out from bottom of transom with silicon from factory.
If I understand correctly it is this that I should "bend" down with chisel to get the effect I'm looking for.
From about 3" to 21" from both outside edges, bend maybe as much as 1/16" down (starting at about 1/32" to be safe).
Is that about right?
Mike |
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Posts: 3469
Location: Elk River, Minnesota | Hi Mike,
That sounds about right. The only part you will bend is the most rearward portion behind the row of rivets. I'd go 1/8", then test... If it is still not enough, go a touch more....but you should see a difference overall. If you go too far, you'll know as well, because the boat will not trim up very well.
It sounds horrible to do, but it definitely will work with things. With rear heavy boats such as what you are describing, you are essentially giving the boat a little more rear lift with the wedge.
Steve |
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Posts: 860
Location: NE Ohio | i'd love to see a picture of this!!!!!! somehow i can't believe a boat company like alumacraft would allow something that far out of spec off the assembly line. |
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Posts: 3469
Location: Elk River, Minnesota | Hiya,
The issue is the boat is not out of spec... Everything is just fine. once in a while, they tap a little too much on the rear gap when assembly is complete, and every boat will be just a little bit different. Sometimes they don't peen enough.
The same thing happens with glass boats as well. Sometimes when a glass boat is made, the rear of the boat has a little hook in the hull, making the boat not trim well... People who experience this have found they must get the hull blueprinted and new glass on the hull...lengthy and invasive...
Steve
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Posts: 860
Location: NE Ohio | ahhhh now i'm getting the picture. thanks VMS. |
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Posts: 51
| Thanks much for the advice.
Will be a bit til I can work on it, but will try to keep posted on results.
M |
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Posts: 2
| I have the same issue with my Navigator 175cs: bad hole shot, 115 Yamaha, SS prop 13 x 19.
I read these posts and took my boat from IL to MN for Alumacraft to see about getting it wedged. After a water test I was told my SS prop was only getting 5400 RPM (8 seconds to get on plane) so they tested the recommended 13 x 19 Aluminum Yami prop which reached 6000 RPM. The boat still took 6 seconds to plane out which is far too long in my opinion. They said this is the best you can expect from a 115 on this boat and wedging hull would not help.
I'm not happy with Alumacraft for selling me a "factory matched" boat that takes 6 seconds to get on plane but I guess I'm stuck with it. My only other option is to spend big bucks and upgrade to a 150 but according to this thread it's doubtful that will solve the problem. It sounds like Alumacraft sold a boat with some major design issues and they don't want to own up to it. |
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Posts: 3469
Location: Elk River, Minnesota | Hiya,
Many of the navigator 175's have had 115 hp engines put on them and they do perfectly fine... Many were set up that way which made for a nice price-point in selling. It is not to say a bad boat comes out now and then, but I highly doubt that your boat is the issue.
With the 115 hp engine on the rig, it will not be anywhere near as fast coming out of the hole as the 115 has a smaller engine displacement as the 150 series of motors. Smaller displacement means less low-end torque, thus the slowness coming out of the hole. I am sorry to say, that the only way to increase hole-shot is to go down in pitch or up in HP.
Now...in terms of props, the aluminum is good for all around when the motor is mounted low on the transom (on the transom or one bolt up). If you switch to a steel prop of the same pitch, diameter and design, rpms go down about 200 and all you gain is durability. If you switch to something like the yamaha Pro-series prop, or to...say a michigan rapture or michigan ballistic, you might be pleasantly surprised at how it will wake the boat up.
If you are turning 5400 with your current steel prop you are definitely on the low end of things, which would suggest a pitch change to a 17...and for that rig, a 17 pitch rapture or ballistic would be very well fitted for the boat....but there is only one way to find that out. That is...to test them. I used to run a 90hp yamaha on the back of my 165 navigator and went with a 17 pitch ballistic and it was a great prop!! It did everything I needed it to do and I was able to move my motor up to the highest mounted position on the boat without too much loss of handling. That particular prop has very heavy trailing edge and tip cupping to lift the entire boat. And...that particular 90hp motor was the smallest displacement of all the 90hp motors out there... It was always sluggish out of the hole...that was never going to change unless I changed motors. (I upgraded to a 90hp johnson, going from 69cid in the yamaha to 105cid in the Johnson....a huge change)
The rapture, on the other hand, has bigger ears overall, but is vented, which is there to help your hole-shot by allowing some exhaust gasses pass through the hub and into the blades so they spin up to a higher rpm. Once a certain rpm is hit, the exhaust pressure is high enough the exhaust will not pass through the vent holes...and up the boat goes out of the hole.
I'd bet there is nothing wrong with the boat... A correct prop will take care of things. A good 17 pitch rapture or Ballistic but check on the yamaha pro-series also...itwould do you well... I believe Yamaha might be making a 17 pitch pro series at this point. if you are still a touch low on rpms the motor most likely can come up a hole or two.
19 in steel is most likely too much pitch, causing your issues...
Steve
Edited by VMS 5/18/2017 11:59 AM
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