Topic: Need help with KeyWest 18Cc and mounting 798ci HD SI)

[lawdog2985]

Hello I have had this unit for a couple years now and get mediocre SI imaging.  I was just cruising the web, and checking for HB software updates, and saw that some guys are running multiple transducers (ie. shoot thru hull/thru hull/).  I have decent imaging to the starboard side, but my lower unit interferes with scanning to the port, I have no problems maintaining a signal at plane as far depth soundings are concerned.

I already trim my outboard all the way up for SI and haven't been able to scan really any faster then about 5-6mph.  I am happy scanning at that speed but would really like to be able to get better SI from the port side.

I really don't like the idea of drilling a hole in boat to run the through hull, and my boat is heavy, and multilayered fiberglass so I don't think shoot thru hull will work either.  My question is would running a second transom style (XNT-9-SI 180-T) be a viable option?  Second, would this adversely effect my current excellent depth soundings at planning speed with the sole transducer?

Any help would be much appreciated.

[RGecy]

No, you wouldn't be moving the existing transducer, so it shouldn't change the depth readings when on plane.  The new one would only be giving you SI from the port side.

What kind of boat do you have?  Picts of the transom area would be helpful.

Good Luck,

Robert

[lawdog2985]

I will post pics shortly.  I am just waiting for a day of no snow or rain.  Seems like winter just won't give up this year.

[Humminbird_Greg]

Sounds like a second XNT-9-Si-180-T transducer and the AS-Si-LR-Y splitter cable would work for you but let’s wait on the boat pictures first.

[lawdog2985]

Just let you guys know I appreciate your interest I have boat all covered right now, and its rained everyday I have been home since posting this.  I intend to get out there this coming Monday to get some photos. Thanks again and pictures to come.

Also while Im thinking about it can somebody advice if transducers from 798 can be used with 899ci HD Si.  Its on sale at Bass Pro, and I was thinking about upgrading this would give me my second transducer to I was thinking.

[Humminbird_Greg]

Yes, the 798’s transducer can be used with the 899ci HD Si unit.  In fact it is the same transducer that gets shipped with the 899 unit.  Many opt for the larger HDSi transducer (XHS-9-HDSi-180-T) though as the 898 can use both the 455kHz and 800kHz Si/Di frequencies plus the 455kHz Si/Di sonar will be more detailed.  The 798 can use the same HDSi transducer and will have the more detailed Si/Di sonar (which some cannot see on the smaller display) but it cannot make the 800kHz Si/Di frequency.

[lawdog2985]

Thanks Greg for the fast response. This is probably a stupid question could I use one 800khz transducer, and one 400khz transducer.

[lawdog2985]

with the 899, sorry forgot that part.

[Humminbird_Greg]

You could but both sides of the Si sonar should look different.  You would not get any good 800kHz Si/Di sonar out of the 798’s Compact Side Imaging (CSi) side.

[lawdog2985]

Cleared up a little this afternoon and got the cover off to get some photos.   Please advise.  This location after much trial and error gave the best all around signal.  Imaging to the port side more or less sucks but to the starboard is not too bad.  I think part of my problem has been range setting.  The screen on the 798 I saw one posting say is really only going to allow for good detail to about 10 ft anymore then that and detail is lost, is this accurate?

[rnvinc]

I would guess that your ladder step is partially blocking the left SI beam ...as the beam extends up past level with the xducer somewhat...

You might think about trying the mount position on the port side...about the same distance from the strake that you have now...this may allow the left beam to shoot under the ladder step...(I would test the mount with double sticky tape so you don't drill more un-necessary holes in your hull)...
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You should get good images out to 100 feet or so...the downside of this is that the 798 screen is so small...structure will be so small in the SI image that you may not be able to descern what it is...

SI image clarity is a combination of boat speed vs chart speed, sensitivity adjusted to match the bottom composition...and a SI Range adjusted so that structure is a "reasonable" size in the image to descern it is structure...

Most try to range (SI Range) at about 2-3 times water depth...(my 1197 has a 10.4" inch screen and I rarely scan past 65' feet left and right)...

There is also the advantage of placing a waypoint on structure seen farther out to the edge of the SI image....and then repositioning the boat to scan closer to the structure to get a better idea of what it is...

Rickie

[lawdog2985]

Rickie,
Thanks for the advice.  This is basically what I was thinking.  I didn't know the SI beam extended up past level.  I will definitely use the double sided tape idea, when I mounted the first side I bolted the xducer to 2*4 to figure out where was the best location, never thought of using double sided tape, sounds much easier. Thanks

[rnvinc]

Rickie,
Thanks for the advice.  This is basically what I was thinking.  I didn't know the SI beam extended up past level.  I will definitely use the double sided tape idea, when I mounted the first side I bolted the xducer to 2*4 to figure out where was the best location, never thought of using double sided tape, sounds much easier. Thanks

Post results....

Rickie