Fish finder setup on 15ft aluminum boat

I don’t know if this fits in this forum or not, but there isn’t a ‘toys for big boys’ forum for those of us with a 70s/80s era 15ft smokercraft, so I’m putting it here :).

I’ve more or less inherited this boat and I’ve really enjoyed fishing in it, but it needs some upgrades. Mainly, I need to get a fish finder. I don’t know what I’m getting for it yet, we will see what’s in the budget, but I have some questions about the best way to rig it up. I’m not too worried about mounting it, I’ll rig something up on the back bench, I’m more worried about how to power the unit.

Let’s just say I buy a Hummimbird 899 SI unit. Knowing that I’m most likely not going to be putting a trolling motor on the boat, and my motor is pull start, what’s the most efficient/cost effective way to power the unit? I don’t think a flasher battery is going to last long running SI, GPS, and that LCD. But do I need to go full bore and spend the ~$130 on a marine battery just to run the fish finder(again, I have no current need for a cranking or deep cycle battery in the boat).

Thanks for the advice! This is going to help me determine how much I can spend on a fish finder.

Took my 597DI, with using the DI the majority of the time, icefishing a couple years ago powered by a vex battery and lasted I think 10-12 hrs.

Considering yours is bigger, maybe 6-8 hrs? Maybe more? Should be fine for shorter trips or the longer ones bring along a couple. Otherwise group 24’s are fairly cheap at big box stores.

I should mention I had the GPS off the majority of time as well, so maybe even less battery time.

nhamm wrote:

Took my 597DI, with using the DI the majority of the time, icefishing a couple years ago powered by a vex battery and lasted I think 10-12 hrs.

Considering yours is bigger, maybe 6-8 hrs? Maybe more? Should be fine for shorter trips or the longer ones bring along a couple. Otherwise group 24’s are fairly cheap at big box stores.

I love the idea of using a flasher battery, mainly because I have a few already and I have a way to charge them. I’m worried about setup though, do I need to worry about it potentially getting wet(should I get some sort of battery box for it).

If I could get by on flasher batteries I’d be happy as a clam as I wouldn’t have to buy a marine battery + battery charger(which reduces my fish finder budget).

Is there any other worries about using a flasher battery? Can I run the cables straight to it, do I need any in-line fuses or anything?

I’ve heard about 3-6 hours, depending on battery quality, on ice with units like the 899. Backlight I think is what would kill you. I would run to fleet farm and pick up a smaller marine starting battery for $45-55.

I’d buy your sonar, hook up the vex batteries and see how it performs and is something you would want to deal with. If it aint go pick up a cheap marine. I’m in the boat if you can use something you already got that’s just sitting around anyways why not.

I always had a fuse on my power cord, don’t know if you need it for small batteries but cheap insurance. To keep the battery from bouncing around I kept it in a crown royal bag with foam around, bungeed to a spot in the boat. Fished in rain quite a bit with it and never had issues.

Good advice above on the batteries.

A note of caution for mounting an SI transducer on a smaller boat. Remember that you need to have a clear line of side for the side imaging to work. Meaning that there needs to be enough room between your transom and lower unit for the transducer to “see” through.

The reason I bring it up is the size and age of your boat. Hope you can avoid the issues I hit the other month.

More details and pics here: http://www.in-depthoutdoors.com/community/forums/topic/new-999-with-side-imaging-and-im-screwed/

Thanks for the advice guys!

I think I’m going to try it out with flasher batteries for now, maybe rig up a cheap battery box or something.

patk wrote:

Good advice above on the batteries.

A note of caution for mounting an SI transducer on a smaller boat. Remember that you need to have a clear line of side for the side imaging to work. Meaning that there needs to be enough room between your transom and lower unit for the transducer to “see” through.

The reason I bring it up is the size and age of your boat. Hope you can avoid the issues I hit the other month.

More details and pics here: http://www.in-depthoutdoors.com/community/forums/topic/new-999-with-side-imaging-and-im-screwed/

I actually remember this thread! My understanding is that the 899 uses a more compact transducer than the 999 or 898 for instance. Would I still run into the same potential problem?

Just to quench my curiosity, how does this thread get moved away from general discussion when stuff like ‘alumacraft vs lund’, and ‘another garmin question’ stay there?

Looks like the 899 uses the XNT 9 SI 180 T transducer. Which doesn’t stick out nearly as far as the XHS 9 HDSI 180 T.

You might be safe with that shorter transducer or you might not. Measuring the distance before buying doesn’t cost you a thing. Compare the distance between the lower unit and transom against the advertised length for the ducer. Add a half inch of you’re going to put a mounting board on it.

Advice I’m giving myself in hindsight.

On my boat it wouldn’t have mattered between transducers, just no room. My solutions were to only get SI on one side, add a second transducer, or give up while putting the money towards a newer/bigger boat. I chose the last option.

Your other question is one for the moderators. I know my transducer thread was appropriately moved out of General Discussion over to the Gear Forum too. was curious as well but didn’t care enough to ask anyone.

I will absolutely measure before buying :), that is sound advice.

I had the same problem setting up my 15 foot boat. I picked up an 18 amp hour mobility scooter battery from Amazon for under $30 and run all my electronics off it (Lowrance Elite 5 HDS, bow and stern lights and pump) even though I have a marine battery and trolling motor. The scooter battery fits in a standard waterproof ammo box with a little filing under the lid. I hooked my electronics up to a protected marine bus bar, ran wires through the box lid to connect to the bar. No interference issues and I can pop the box/battery out no problem. Running everything, I’ve never come close to depleting that battery in a day.

I just got home and measured, it looks like I have between 5 and 6 inches to work with(depending exactly where I mount the transducer), so I think I’m good there(thank goodness).

Hey Pat, just curious if your Merc has a way to adjust the angle your motor sits in the water? I am really showing my vast knowledge of boat motors and terminology here, but my evinrude has like 4 ‘trim settings’ you can use. I don’t mean trim like ‘I can lift my motor up 50% of the way and it clicks into position’, I mean there’s like 4 slots that adjust the angle of the motor as it sits in the water naturally.

I guarantee everyone here knows a lot more about outboards than I do, but if you look at the 2nd picture here:
http://smalloutboards.com/e4084s.htm

You can see 5 holes(one has a pin in it) that adjust the angle of the motor(I’m guessing so you can setup your motor to sit properly, depending on the shape of your transom). They are about even with the electrical cord in the background.

Anyways, just curious if your merc has a similar thing and whether adjusting that a bit would have bought you a few more inches(at the cost of the motor being slightly ‘trimmed up’ at all times)

Someone can now come in and tell me what those things are called exactly so I can stop sounding like an idiot.

@Philtickelson

Yes, my outboard does have an option to “tilt”. It’s manual and at the halfway up point. Technically that was another option for me that wouldn’t cost any money. If I tilted it up then the si ducer would have had a clear line of sight to both sides.

That said I was concerned about losing boat control. I do a ton of back trolling and didn’t think I would like my control at halfway up.

Yes, this is an option for you and probably in better shape than I. If you’ve got 5-6 inches of space and 4 “trim” settings then you’ve got options. Could be that you have a small overlap while fully down but raise it up to setting 1 and then you’ve got the best of both worlds. SI and good boat control.

Testing and measuring is advice again here. Go play with your motor and use a tape measure. See what the options look like. Once again, my hindsight at work here.

took a second look at the pics. I don’t think you have 5 trim setting per se. I think what you have is points to set how low/high it goes when “trimmed” in the down position.

ex. on my little boat it was riding high in the bow and had trouble planning. I changed out the pin to a different setting. Voila, planes great with a couple people in the boat now.

ex. on my little boat I have 3 trim settings. All the way down. All the way up. A middle point also called shallow drive.

Logan,
I used to run that same 40hp rude (tilt/trim) on a 16′ lunker with the HDSI duecer. It’ll interfere unless you trim up some.
When that baby blew up i ran a 25hp with the trim holes. I’d “trim” it up a notch when i wanted to scan a bunch but it only partially gets in the way of your SI anyway. Eventually i fixed the 40HP and also the lower unit when that went too. Nice motor for that sized boat for sure! You will wish you had electric tilt/trim cuz that baby is heavy.

If you put a fish finder on a 15 foot boat, it must cost more than the boat/motor/trailer

If I have partial interference I can live with that. I actually have quite a bit of clearance between my transom and lower unit currently, if I notch it up one notch I will have even more.

I can hit mid-high 20s with a dinged up prop when I’m by myself, which is plenty fast for this boat. I don’t foresee me heading to any big bodies of water with it.

The mechanic that fixed some wiring in the motor said that it’s a $1300 motor, so for now the motor is the most expensive piece of the package(barely). I don’t mind though, I think the electronics are going to help me catch more fish than any other money I put into it.

The trailer and boat itself aren’t worth crap though haha. The trailer is a whole other animal. One of the rollers is welded on to the trailer and about 75% of that weld is broken loose. At least it’s got new tires(and a spare).

The next project is getting some seats in there, which isn’t nearly as easy as it should be when you have a floor that probably should be replaced and thin aluminum benches that you can’t get underneath without cutting through them(and removing a lot of foam).

You’d love what I have in mind for mounting the depth finder though, I’ll have to send you a picture when it’s done.

Awesome Logan!

Welcome to the money pit!