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I purchased my first vessel about two months ago used. got a great deal but been working on small issues with the boat. It has an icom 502 with a 4 ft antenna on the t top. The unit works great, the previous owner left the antenna up and smashed the tip off of it so I plan on replacing it. I generally fish no more than 40 miles offshore and was wondering if the 4 ft antenna will suffice? I was thinking of upgrading to an 8ft....Any thoughts?
VHF radio is line of sight. So the higher the antenna is, generally the better the range. If your mount can support the added movement an 8' antenna can impart without failing, I'd go with the 8' antenna. I'm presuming that you have a substantial stainless steel tilting bracket - I'm not talking about that failing, but rather what you have that mount attached to. If it can handle the greater amount of swaying a longer antenna can impart, get a GOOD QUALITY 8' antenna.
__________________ Joe
His Doghouse Too
2004 Luhrs 38 Open
ACN Independent Rep
It in't just range, its amplification too. A 4' antenna has 3db amplification, while an 8' is 6 db, meaning in theory, in line of sight, it has 2x the range (some 21' units are 9 or 10 db). Line of sight is deceiving - it is the combined height of the transmitting and receiving antenna that equals range. I can pick up the USCG from NY when I am more than 50 miles out on my 8' antenna (USCG antenna's are really tall), I don't think they can hear me, but I never tried from that far out.
No question about it. If you are replacing it anyway, go for the 8' and buy high quality. I just put an icom on my boat and paired it with an 8' digital antena. I did this because on my last boat I had a base model ICOM with a very good quality antena and it had a noticibly better range on it than the other boats I was fishing on. At the very least, it is a conveniance to communicate and be heard at the most important this could save a life if the communication is critical. Not the place to commpromise in my opinion.
No question about it. If you are replacing it anyway, go for the 8' and buy high quality. I just put an icom on my boat and paired it with an 8' digital antena. I did this because on my last boat I had a base model ICOM with a very good quality antena and it had a noticibly better range on it than the other boats I was fishing on. At the very least, it is a conveniance to communicate and be heard at the most important this could save a life if the communication is critical. Not the place to commpromise in my opinion.
Frank
That's what I was thinking. Can you recommend an decent, affordable antenna? Possibly post a link? The setup I have now already saved my arse once, but I was only 12 miles from land....
I purchased my Digital (brand) antenna from Jim at BOE. He's a THT sponsor, and his prices are among the best around. When you call, you very often get him directly, and he'll help you choose the best antenna for your application. And he ships VERY quickly.
On one of my boats (the center console with t-top) I've got an 8' Shakespeare Centennial (about $60 shipped) and an Icom 422. Earlier this year in the 'noreast, I got a confirmed loud and clear radio check from a guy 55 miles away. No need to waste good money on any over rated antenna. There are a lot of boats out there with Shakespeare Centennials a good antenna at a good price. Main thing is to make sure all the connections are good particularly at the coax and PL-259 connector. I prefer solder.
I would second Squidd and the Shakespeare Centennials or their (Shakespeare's) next higher priced line. Not much point in going beyond that. Before you buy a Digital, see several of the discussions in this forum in the past one to three months.
If only the tip is smashed on your present antenna it won't affect performance (unless it opens the center so water can run into it.) Might try epoxying the end to keep water out and see what range you are getting. May be all you'll need.
Gain antenna's do work better than unity antenna's. i.e. unity no gain. But you pay a price. Gain antenna's work by compressing the signal into a direction that you want it go. On commercial business antenna's they will quote in specs what's called beam tilt. The antenna's will work better at the horizon than up close because the signal is being compressed to work better at distances. The higher the gain the more the signal is being compressed. If you have a high gain antenna and the boat is rocking from side to side at anchor you will notice the signal fading in and out. This is because the station you are listening to is constantly going into and out of the sweet spot on the antenna. A unity will not fade out at all and a 3db gain will do less so than a 6db and so forth. Think of it like a water house that is parallel with the ground, high db gain the water is a focused stream. Unity it is a spray. My advice if possible get as high an extension as possible with a 3db gain. Height is more important than the gain of the antenna. With the 3db gain you are getting some gain without the disadvantage of severe signal fade. And the added height will improve coverage more so than any gain antenna could do. Also depending on how much of the tip you lost it could detune your antenna to the point it could burn out the PA in your radio. Each frequency has an antenna length to go with that frequency and if an antenna is too short ot too long some of that power will not be disipated by the antenna and go back into your radio. Mobile radios can accept 10% reflected power. Any more than that and the finals in your PA will be fried. As marine radio's are pretty cheap the cost to repair would be too high. That means replacing it. My knowledge comes from 20 years in the comercial two way business.
That's what I was thinking. Can you recommend an decent, affordable antenna? Possibly post a link? The setup I have now already saved my arse once, but I was only 12 miles from land....
I would go to a proffessional and ask. That is what I did. Someone who is in the business should be able to recommend a good antena
I would go to a proffessional and ask. That is what I did. Someone who is in the business should be able to recommend a good antena
Good Luck
Yes, there is a place in the bayou here that specializes in radio and navigation systems on the shrimp boats. I'm going to stop in there next time im in the area.... I need that radio to be 100% if im 40 miles offshore and some thing goes wrong.
ICOM 502 4FT OR 8FT antenna? 
