MonkeyBird747
Petty Officer 2nd Class
- Joined
- Aug 5, 2020
- Messages
- 112
Hello all! New to the forum and this is my first post. Hope it's not too much of a doozy! I'm landlocked and only boat on small-ish lakes. Mostly just fishing, with some cruising here and there.
Picked up a new-to-me '73 Mariner 18' center console with a 1985 50hp merc. Previous owned had put some work into it and looks to be a nice boat. After a test outing on the lake I decided I'd like to put a little bigger motor on (I had already anticipated this), along with a fuel capacity upgrade. The 50hp was fueled by a single 6.5 gallon tank, and we burned through most of that during a half day fishing trip on a pretty small lake. It's enough motor to get up on plane, and cruise about 20mph just shy of wot.
I started digging into the subject of fuel and began to have some concerns. I don't know what the original configuration was, but this one has an enclosed area under the splash deck. The area is accessible by hatch, and inside was stored a portable 6.5 gal fuel tank next to two unsecured marine batteries (eek). One cranking battery, and one (uncharged) battery that runs all accessories (bilge, navs, fishing lights, stereo, bait well, and fish finder). The area is not exactly air tight, and there are a dozen or more 3/8' holes that were occupied by some unknown furnishing in the past (see pics - maybe a hinged bench seat or hatch?). Plus there are some pretty big holes for motor cables routed through the splash deck as well. Still, based on what I've read here, seems enclosed enough to me to be a no-no for jerry cans and batteries to be bunk-mates. I'd like to hear thoughts on that though.
So, my thought was to relocate the cranking battery and accessory battery to beneath the center console, and add a permanent fuel tank beneath the splash deck in the enclosed space, along with an external filler neck and vent. Trying to keep this on a tight budget and use readily available components. I can only find a 13 gallon Moeller poly that I'm sure would fit. They have a 19 gallon, but the fill neck needs to be on the port or starboard side for vertical clearance, and the 19 gal has it in the middle, which won't work. Other than those it would have to be a custom aluminum job, which is probaly going to be cost prohibitive.
I'm thinking of a 90 or 115hp motor. Probably be a 2-stroke and could be late 90's early 2000's based on the budget. Not sure the 13 gal is going to cut the proverbial mustard. Trying to avoid having a lot of gas cans in the way on the deck, and this splash deck area is about the only place to store them. The lake I mostly fish is only 3000 acres, so maybe fuel endurance isn't such a huge consideration for fishing trips.
Said all that to ask these few questions:
1. Am I overthinking this fuel tank issue? I could just relocate the batteries and put two 6.5 gallon portables in the enclosed area. It may be naturally vented enough as is, or I could leave the hatch open (or just remove it as in the pictures) to let them breath. I could manually swap tanks as needed, plumb together, or install a selector valve. They would still be in there with the bilge and bait tank pumps, though.
2. If I install the Moeller below deck poly, would it then be safe to have batteries in the same compartment?
3. Is it normal to have a single battery running all the accessories like that? Should I relocate some items to the cranking battery or the trolling motor batteries up front? I have a Minn Kota 3-bank charger on board, which takes care of the two troller bats and the accessory batt.
4. I've been focused on the 90 and 115hp, but should I consider something like a 75hp as well? I think the boat is a bit heavier than it was originally.
5. Am I missing some more sensible options on all fronts?
Here are a few pics to get started. I'll try to get some better ones. Pictures have descriptions that hopefully tell the story.
Thanks everyone!
MB
Picked up a new-to-me '73 Mariner 18' center console with a 1985 50hp merc. Previous owned had put some work into it and looks to be a nice boat. After a test outing on the lake I decided I'd like to put a little bigger motor on (I had already anticipated this), along with a fuel capacity upgrade. The 50hp was fueled by a single 6.5 gallon tank, and we burned through most of that during a half day fishing trip on a pretty small lake. It's enough motor to get up on plane, and cruise about 20mph just shy of wot.
I started digging into the subject of fuel and began to have some concerns. I don't know what the original configuration was, but this one has an enclosed area under the splash deck. The area is accessible by hatch, and inside was stored a portable 6.5 gal fuel tank next to two unsecured marine batteries (eek). One cranking battery, and one (uncharged) battery that runs all accessories (bilge, navs, fishing lights, stereo, bait well, and fish finder). The area is not exactly air tight, and there are a dozen or more 3/8' holes that were occupied by some unknown furnishing in the past (see pics - maybe a hinged bench seat or hatch?). Plus there are some pretty big holes for motor cables routed through the splash deck as well. Still, based on what I've read here, seems enclosed enough to me to be a no-no for jerry cans and batteries to be bunk-mates. I'd like to hear thoughts on that though.
So, my thought was to relocate the cranking battery and accessory battery to beneath the center console, and add a permanent fuel tank beneath the splash deck in the enclosed space, along with an external filler neck and vent. Trying to keep this on a tight budget and use readily available components. I can only find a 13 gallon Moeller poly that I'm sure would fit. They have a 19 gallon, but the fill neck needs to be on the port or starboard side for vertical clearance, and the 19 gal has it in the middle, which won't work. Other than those it would have to be a custom aluminum job, which is probaly going to be cost prohibitive.
I'm thinking of a 90 or 115hp motor. Probably be a 2-stroke and could be late 90's early 2000's based on the budget. Not sure the 13 gal is going to cut the proverbial mustard. Trying to avoid having a lot of gas cans in the way on the deck, and this splash deck area is about the only place to store them. The lake I mostly fish is only 3000 acres, so maybe fuel endurance isn't such a huge consideration for fishing trips.
Said all that to ask these few questions:
1. Am I overthinking this fuel tank issue? I could just relocate the batteries and put two 6.5 gallon portables in the enclosed area. It may be naturally vented enough as is, or I could leave the hatch open (or just remove it as in the pictures) to let them breath. I could manually swap tanks as needed, plumb together, or install a selector valve. They would still be in there with the bilge and bait tank pumps, though.
2. If I install the Moeller below deck poly, would it then be safe to have batteries in the same compartment?
3. Is it normal to have a single battery running all the accessories like that? Should I relocate some items to the cranking battery or the trolling motor batteries up front? I have a Minn Kota 3-bank charger on board, which takes care of the two troller bats and the accessory batt.
4. I've been focused on the 90 and 115hp, but should I consider something like a 75hp as well? I think the boat is a bit heavier than it was originally.
5. Am I missing some more sensible options on all fronts?
Here are a few pics to get started. I'll try to get some better ones. Pictures have descriptions that hopefully tell the story.
Thanks everyone!
MB
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