Bow wander at speed.

lcdr frank

Seaman Apprentice
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May 25, 2008
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Bought my first new boat. 16 foot pole cat by 33 Strike Group. 50 Merc. This is an aluminum catermeran. After I get her on a plane I experience the bow wanders from side to side.There is no slack in the steering or any slop in the eng mounting.I can trim the eng up and that seems to help.I am runing a Merc 3 blade stainless prop. I am going to try the trim tab on the foot next time out. What yall think?

LCDR Frank
 

alldodge

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I think it's the nature of the beast, very light boat with a cat hull. Real easy to chin walk that style of boat
 

Bondo

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Ayuh,.... Just for S's, & Giggles, measure the keel lines of the 2 keels, 'n see whether they're parallel or not,...
 

Thalasso

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Sounds like you need to get the bow higher. Trim the motor up more
 

Watermann

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Post up a pic or 3 of that aluminum cat and the way you have her rigged up... please!
 

lcdr frank

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May 25, 2008
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The whole boat shifts as if I let the steering wheel go and then recovered and over steered .We are going out after we get through Turkey Day. The ride in rough water or crossing a wake is just amazing. At anchor stability is remarkable.
 

ondarvr

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Apr 6, 2005
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Cats are very sensitive to weight location and balance, move some weight toward the stern and get the bow up.
 
Last edited:

Texasmark

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Dec 20, 2005
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If you are pulling to one side when you let go of the steering wheel then you need to tweak your trim tab....the little zinc thingabob just under the horizontal plate just over and aft of the top of the prop. Undo the bolt till it moves freely and turn the rear of it in the direction the boat is pulling. Trial and error till you get it right. That is different than "over steering" aka bow wander....that occurs randomly in both directions.
 

lcdr frank

Seaman Apprentice
Joined
May 25, 2008
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36
If you are pulling to one side when you let go of the steering wheel then you need to tweak your trim tab....the little zinc thingabob just under the horizontal plate just over and aft of the top of the prop. Undo the bolt till it moves freely and turn the rear of it in the direction the boat is pulling. Trial and error till you get it right. That is different than "over steering" aka bow wander....that occurs randomly in both directions.

I have just got to go this week end. I turned the eng trim tab to opposit side to change the direction . Seem a little better especially when I trim the motor up .Push come to shove I will call the boat builder. All this happens from on plane(15k) to top end (24k).A couple times It rod like a Caddilac, I just could not repeat regularly.


Frank
 

Stumpalump

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Dec 5, 2013
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413
Motor is too high not allowing enough trim is my wag at the problem with out seeing it. Too much weight and hull in the water on the front or not enough trim if it's your first boat. Me...I'd do all that then call manuf. If you could get them to run it and blueprint it then you will say wow!
 

lcdr frank

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May 25, 2008
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First NEW boat.First Cat boat.Had many boats over the years and most required some tweaking. On power up this one goes up level...no bow rise...just a level attitude. Cornering without leaning.I am sure I will get it sorted out. The boat handles choppy water so well my wife no longer turns green.
 

lcdr frank

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May 25, 2008
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After adjusting the trim tab from left to right. no real improvement. I just set the trim tab dead straight and put the trim on the motor up and it made a big difference. she tracks much better Wish I had a trim angle gauge to duplicate it over again. I just keep hitting up at throttle till it worked. now if the fish would start bitting I would be very happy.

Frank
 

alldodge

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Trim should be used by feel, once your on plane trim it up until the boat stops increasing speed and starts to slow. Then down a bit and your good. Any change in weight, wind, or direction will cause a change in trim
 

smokeonthewater

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Dec 3, 2009
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9,838
You CAN count seconds if up trim from full down to get it close but as dodge said it's always a little different... I trim up watching the tach and speed till no improvement OR it starts to porpoise and back off a little...

I regularly fiddle with it to squeak out a touch more speed IE better efficiency.
 

lcdr frank

Seaman Apprentice
Joined
May 25, 2008
Messages
36
I ran a test at speed wot 5200 to 5300 rpm, As trim cam up the rpm only rose slightly but broke the surface and cavitated. I droped trim back for a 2 count and started again. I am going to contact the boat builder for some tips.

Frank
 
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