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Stern drive handling (358)
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Author:  Ben [ Sun Sep 23, 2007 10:39 pm ]
Post subject:  Stern drive handling (358)

I've got a question that has been on my mind a little but is now much more on my mind. I was out on a friends Searay 340 dancer with 8.1HOs and V-drives. I mention this because last year I participated in a lease share arrangement on a similar Searay and that was the boat I learned to handle 30+ foot vessels on.

On to my question... I have a 2007 Vista 358 with the 5.7 OSXi sterndrive configuration. The boat handles pretty well and is fairly quick (though being out tonight on the big blocks I could certainly tell the difference in torque) but I have noticed a little bit squirely handling in several conditions. The first is that the straight line performance on the boat isn't so straight. If I make even a small correction it takes a long time for the correction to take effect but once it does the boat tends to sort of run-away with the correction. This is a problem at both low speed and high speed though the effect can be larger at high speed. I have to assume a fair amount of this has to do with the sterndrives and the fact that if they are anything but perfectly straight they are going to "push" the boat off straight pretty dramatically. The thing that I've noticed is that there is pretty much no straight, it's always wandering slightly one direction or another and needing to be adjusted. This almsot has me wondering if there is something going on like the drives are slightly misaligned such that one is always a little crooked or something like that.

I'm wondering if others with sterndrives, particularly twins, have a similar situation or if this is something that I should be talking to my dealer about. It was nice to drive the SR tonight and realize what it was like to not have to constantly correct, correct, and then correct agian.

Thanks
Ben

Author:  MCLKS [ Tue Jul 22, 2008 3:13 pm ]
Post subject:  Re: Stern drive handling (358)

Ben,

I have a Vista 298 with twin 5.0's and the boat is very responsive to movement of the drives. What I have noticed that may be similar to your issue is the boat tends to roll on its keel. For lack of a better explanation, it is similar to when you cross over a small wake from another boat or wave action. I noticed that the "attitude" of trim on the drives and the trim tabs have an effect.

The aft portion of our boat bottoms are very rounded (at least in the last 5-6 feet. If the attitude of the boat is running more to the aft, you will notice a change in response. This feeling may be increased on IO models given that you have greater trimming adjustment where inboards are fixed and only have trim tabs.

Author:  Brett248Vista [ Tue Jul 22, 2008 5:12 pm ]
Post subject:  Re: Stern drive handling (358)

All I/O boats corkscrew at displacement speed. You learn that very little input is needed to correct, sometimes no input at all and the boat will straighten out on it's own. I also put my tabs down which helps the boat track more straight at displacement speed.

Author:  Better Luck [ Mon Jul 28, 2008 6:53 am ]
Post subject:  Re: Stern drive handling (358)

I don't notice what you are referring to. Our boat tracks straight. I am continually looking back to see my wake and to notice if it is not a straight line. A friend of mine told me the straighter you go the better fuel economy you have.

I agree that very little input is required to change direction.

Author:  jrcinnh [ Mon Jul 28, 2008 8:38 am ]
Post subject:  Re: Stern drive handling (358)

In calm condition or at sharp angles to the waves, my boat seems to track great and run smooth. I run with the trim tabs all the way up and the engine trim just a touch above full down. The boat will run great there from 3200 to WOT.

In mixed conditions with lots of random wakes or at oblique angles the boat needs trim tabs. Without tabs the boat seems to twist and follow the waves. With the tabs down it gets a more planted feel.

I have the VP 5.7 dual prop outdrives.

Author:  Better Luck [ Wed Jul 30, 2008 4:47 pm ]
Post subject:  Re: Stern drive handling (358)

jrcinnh wrote:
In calm condition or at sharp angles to the waves, my boat seems to track great and run smooth. I run with the trim tabs all the way up and the engine trim just a touch above full down. The boat will run great there from 3200 to WOT.

In mixed conditions with lots of random wakes or at oblique angles the boat needs trim tabs. Without tabs the boat seems to twist and follow the waves. With the tabs down it gets a more planted feel.

I have the VP 5.7 dual prop outdrives.


I completely agree with that! Well said.

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