LM18 Houston Tx

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Cbuf
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Re: LM18 Houston Tx

Post by Cbuf »

TomW1 wrote: Mon Jun 07, 2021 8:29 pm Yep Chuf there is not much difference in the 40HP weights. 20- 30 lbs will not make much difference in top speed, maybe 1-2 mph for a 40HP. Motor weight is a small part of the over all weight of the boat and load, less than a 1/4. :D

Tom
I agree with your statement. I used the planned weight of the motor to plan battery position, live well position, and console position. I floated the boat with 240lbs of 5 gallon buckets of water to simulate the motor weight that planned out where everything need to go. Not required, but I didn't want to cross my fingers. The test made me realize that my big trolling motor battery needed to be as far forward as possible.

Cbuf
240 lbs.jpg
See my LM 18 build here.
viewtopic.php?t=64254
See my LM 18 Questions here.
viewtopic.php?f=2&t=64299&hilit=lm18\
Finished Boat Here
viewtopic.php?f=25&t=65173

Jeff
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Re: LM18 Houston Tx

Post by Jeff »

Nice test Cbuf!!! Jeff

TomW1
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Re: LM18 Houston Tx

Post by TomW1 »

Very nicely done Chuf.

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

ericwensel
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Re: LM18 Houston Tx

Post by ericwensel »

I had decided to put the two trolling motor batteries just aft of frame B and the starting battery aft of frame E. I originally wanted to put all three batteries together at frame B but did not want to spend the money on the required 1/0 cable. After giving it some thought (and seeing Cbuf's post), I am thinking I will go back to my original plan. The single battery weight is probably 50-60lbs and it will offset the motor weight some. The nice thing about keeping them together (in addition to weight distribution) is that i can jumper the trolling motor batteries to the starting circuit if needed.

I am basing the 1/0 on the assumption a 40hp draws 125amps and i am limiting voltage drop to 3%. the assumed length is 25ft. I am going to run the wire in a conduit under the inwale/gunnel rather than below the sole. I only have one straight through conduit running from B to E (under the sole) and it is being used for fuel. I have another from B to the console and several from the console to E but that would add more length.

I am still thinking 40hp even though for most motors the 50s are close to the 40s in weight as you say. I just think 40hp is more than enough but not so much that I can convince myself to go with the 30hp.

This weekend i am going to glass the sole between A and B and set the tank. Thanks TomW1 for the suggestion on mounting the tank. I like the approach. I think i will set the tank on HDPE pads secured to the tank with 5200 (as described in the article). However, I think i will use the bolts to secure to the tank to the deck. I also hope to install an additional bulkhead aft of frame B. I am calling it BB and between B and BB is where the batteries will be located.

Cbuf
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Re: LM18 Houston Tx

Post by Cbuf »

This is just a consideration for you to thick about. I think I have it somewhere in one of my posts, but motor under 50 don't require many cranking amp to start the motor. With todays EFI motors they generally start at the turn of the key. Harley batteries turn out more than enough cranking amp to start any motor. My starting battery is only 13 pounds. My deep cycle troller is 60 pounds. I have the 2 batteries linked together with a Blue sea Automatic charge control relay(ACR) and a battery combiner switch. Once the little battery is at full charge it charges the trolling motor/house battery. Even if I run the trolling motor battery to 0 the starting battery will start the motor and the 14 amp output is plenty to run the boat to make it home. Most of my fishing is tide based, so I have only had a couple what I would call full days on the water 8-10 hours, but I have never run out of juice. It does require heavy gauge wire to like you said however to run from the front of the boat to the back.

cbuf
See my LM 18 build here.
viewtopic.php?t=64254
See my LM 18 Questions here.
viewtopic.php?f=2&t=64299&hilit=lm18\
Finished Boat Here
viewtopic.php?f=25&t=65173

Mojosmantra
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Re: LM18 Houston Tx

Post by Mojosmantra »

Eric - looking back and admiring your paint job. I’ll be painting soon and will also be using Alexseal. What type of roller did you use? And did you use any additives/thinners other than the rolling (no tip) additive?

Trent

ericwensel
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Re: LM18 Houston Tx

Post by ericwensel »

Mojosmantra wrote: Sat Jul 17, 2021 9:14 am Eric - looking back and admiring your paint job. I’ll be painting soon and will also be using Alexseal. What type of roller did you use? And did you use any additives/thinners other than the rolling (no tip) additive?

Trent
I just used the roll (no tip) additive. I used no other additives or thinners. I used high density foam rollers. I seemed to have better luck with the foam roller over the mohair.

ericwensel
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Re: LM18 Houston Tx

Post by ericwensel »

I have made slow progress of late but i have done some work.

Painted inside between bow and frame B (actually what i call BB which is an extra frame that i added to make a spot for batteries).
I could not bring myself to use the Alexseal paint even though i have plenty. I used TotalBilge which was easy to apply and looks good.

I added the hatch frames between A and B and B and BB. The A-B hatch is just large enough to remove the gas tank. It is forward enough to where i can access the are forward of frame A and offers a good bit of storage forward the tank.

Image

I also built the hatch frame for the hatch between E and T. It has not been glued in yet but i will glue it in after i paint the bilge. I have just one coat of primer it so far.

Image

ericwensel
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Re: LM18 Houston Tx

Post by ericwensel »

A little more progress
Working on hatches now. Also put a couple more holes in the hull for various items including bow eye, transom u-bolts, fuel tank vent, etc. still need to put in a thru hull fitting for the bilge. Also put in the rod tubes.

Image
Transom holes for u-bolts and drain.

Image
Bow eye.

Image
Rear hatch.

Image
Hatch in rear side compartment.

Image
Rod tubes.

Jeff
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Re: LM18 Houston Tx

Post by Jeff »

Nice progress!! Jeff

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