Fishfinder Advice

[mcleaves]

I am looking to upgrade my fish finding capabilities but am thoroughly confused. I have a Garmin GPSMAP 168 that has a 150 watt sounder built in.<br /><br />I was initially told I want a unit with at least 350 watts and something that will identify structures. When I look at that class of finder they are all dual frequency. Looking at fishfinder-store.com/ease481.html <br />you see the quote i put at the end of this post.<br /><br />I have a budget of about 200.00 and fish mainly in 50-100 ft of water, although I could go as deep as 200 ft on a rare day. Mostly looking for Cod on the bottom. Any advice would be great!<br /><br />If you need a deep water finder this is the right one, however, if you are fishing inland waters a dual frequency unit is the wrong choice, you should select a single frequency unit because on high sensitivity it has a 60 degree 200 Khz cone verses the dual frequency that only has an 8 degree 200khz cone. The 200khz is the only frequency that sees fish.<br /><br />The Dual Frequency is great in deep water and very poor in shallow because the 50khz in the dual frequency shows deep bottom structure but not fish.<br /><br />(edited forbidden link)

 

[JB]

Re: Fishfinder Advice

http://www.iboats.com/mall/index.cg...id=248074&view_id=248074&search_type=category

 

[mcleaves]

Re: Fishfinder Advice

Thanks for the link JB, but I don't have a problem finding fish finders (no pun intended). I'm having trouble understanding what it is I should buy, or if I should buy anything. I can find a 350 watt or I can find a single scan but the combo seems to be hard to find. <br /><br />But the real question is what SHOULD I buy if I am operating in 50-200 feet of water?<br /><br />In other words I have a single scan 150 watt one built in to my GPS. If I am stuck with a 200 watt limit because I need a single freq one, then is it worthwhile or is my 150 enough. I'd like to be able to see structure and either I'm not using mine properly or it doesn't do a good job. <br /><br />Mike

 

[Boatist]

Re: Fishfinder Advice

First you need to understand power. Power is given two ways as peak to peak or as RMS. RMS times 8 equals PeP. Example 500 watts RMS = 4000 watts PeP. I have a fish finder that has 375 watts RMS or 3000 watts PeP. At 200 KHz frequency with a 20 degree transducer could only see fish out to about 250 feet of salt water. By changing to a 8 degree transducer could see fish out to about 400 feet of salt water. The power is considrated into a narrower beam so you get better returns.<br /><br />200 KHZ transducer 20 degree is good in fresh water and it showes better detail of fish. In shallow salt water out to at least 150 feet the 200 khz is still a better transducer. The 50 khz transducer penetrates much deaper and in deep salt water will show more fish. The 50 khz transducer does not give as fine a detail. A school of fish may look like one big blob. The 200Khz transducer of the same school may show a bunch of single arches close together.<br /><br />In your quote above many manufacturer with a dual frequency transducer 200/50 Khz may assume your useing it is deeper salt water so they select a cone narrower cone angle which works better in salt water. The standard cone angle for most 200 Khz transducers is 20 degrees. The standard cone angel for most 50 khz transducers is 45 degrees. Example Lowrance 200/50Khz transducer, the 200 khz is 12 degrees cone angle and the 50khz cone angle is 36 degrees.<br /><br />The up to 60 degrees cone angle Lowrance and Eagle are talking about is a 20 degree transducer. It very misleading to say can see fish up to 60 degrees. This is true for all 20 degree transducers, but the reality is still only about 20 degrees is useable. If you turn the sensitivity up high enough to see fish out in the 60 degree range the screen will be all black because of the stronger returns from the center of the cone. To confirm the up to 60 degree cone angle is really a 20 degree transducer go to the site claiming 60 degrees and the check the transducers they sell. You will not find one rated at 60 degrees.<br /><br />Go to Lowrance.com and go thru the sonar tutor. It explains a lot about transducer and how the unit displays fish.

 

[whofan]

Re: Fishfinder Advice

http://www.iboats.com/mall/index.cgi?**********=895176245&*******=847470991&search_in_category=t&view_id=52870&page_number=4&keywords=brand_76_Eagle_Electronics&category_id=248093& list_time=1149680324<br /><br /> Keep your Garmin for the GPS feature. <br />Then have a stand alone graph. <br />For a sonar this eagle 480 is the best deal going for the money.