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I figured I’d move my stuff over to the build thread now…. Setting this jig up has been a pain in the a**! I still have some adjustments to make to get everything flush and square. Here’s some progress pics not in order sorry!

~Ryan

A little more progress! The tunnel wasn’t too bad to build… question for you vets! what are your thoughts about countersinking a brass fitting with a ball valve, hose, etc, to have the ability to vent or non-vent the tunnel. I wasn’t sure if water running across the surface of a fitting (even if recessed) would disrupt the water flow enough to negate suction?

I stole the 1/4 round idea from one of the gents on here.

~Ryan

First duh! Moment… cut one of the frames too long! No big deal though. I’ll cut it to size tomorrow.

Just about ready to spot weld!

Looks good Ryan. Are you not using spacers intentionally?

Yes, just dry fitting the panels. I went back and spaced everything out this morning. Everything fit surprisingly well! I though something might be wrong… lol

Anyone see anything crazy? I’m getting ready to tape it tonight.. the hull looks fair (for the most part).

Looks great from where I'm sitting! Is the bottom flat near the stern to your satisfaction?

Maybe jumping the gun, but you need radiuses on the chines and transom for glassing.

Might be what Jeff was getting at..not sure.

After you make the radiuses; the transom gets resharpened.

No radius will fail.

Good catch guys! I went back and re-read my plans. For some reason I was thinking the tape stoped at the stern. The plans call for tape on transom and keel.

Wouldn't the tunnel be getting taped in as well?

I figured I’d tape the tunnel in after… it flexes pretty good around that area now, I figured I put the tunnel after I taped it that way there will be minima flex. What do y’all think? I can’t really tape them all together anyways.

All the tapes should overlap; so it really is all the same job unless the tunnel is not ready..

I took your advice fallguy! The tunnel is in! Radius’d the transom as well.
I appreciate the help!

I am not an LM18 builder; just know how to glass some.

I can't catch all your errors, but you would be wise to precoat all those router edges one hour before taping. The edges can suck resins from the tapes which is okay for 1200, 1208,1708 tapes, but not as good for 6 oz. The most important glasswork is the boat bottom and top edge of the transom. Top edge is to keep the transom from blowing open and rotting. Bottom laminates must not have air pockets or they can delam.

All tapes get overlaps, too. No butt seams.

Here’s some more progress pics…. Scored a pretty sweet deal on Yamaha 70 2stroke (overpowered I know!) came with all controls and bobs jackplate. Oh yeah, and me trying to be Hercules ended up with a nice prop gash!!!

Ryan wrote: ↑Sat Feb 05, 2022 5:40 pm Here’s some more progress pics…. Scored a pretty sweet deal on Yamaha 70 2stroke (overpowered I know!) came with all controls and bobs jackplate. Oh yeah, and me trying to be Hercules ended up with a nice prop gash!!!

One of the 17' whalers I used when I was a sailing instructor had one of those Yamaha 2 stroke 70s. Great motor and had a great sound too. Any motor that can survive being driven 40 hours a week by young sailing instructors is a sturdy motor.

While that motor weighs only about 15lbs more than the Yamaha 40HP 4ST you will need to run it at lower rpms. This will not be good for the motor. I have that motor on my OD18 and would not want to put it on it on a LM18, at cruise at 2700lbs I'm at 3300rpms. Since you will be much lighter your rpms will be less. Jacques lists a 40Hp as the max and you will be in the 30's with that, don't go any higher. Keep the Jack plate and sell the motor or trade for a 40. The 70 is way overpowered for an LM18.

Tom

I appreciate the input Tom! We’ll see how it goes, either way I will end up with a Yamaha… sometimes there will be three of us in the boat and that 70 might come in handy to plane quickly.

I also disagree with the 70hp choice as well. The awesome thing is those controls/wiring will work with a 50 or 40 hp two stoke. Ask me how I know!!! Also that 70 is a monster at 228lbs!!!!! The Tohatsu brand motors are the lightest on the market the 40/50hp weighing 209 lbs. The 30 weighing 157lbs. Having so much weight in the back will start making your skiff like a production skiff....stern fat and unbalanced. Not so awesome. These boats are meant to be light. He calls for a 40hp in the plans as the largest.


I went with a 50hp yamaha two stroke (189lbs) on my LM18 tunnel after talking to a guy with a 50hp Tohatsu on his. He is my size (6'5" 230-250lbs) and said it was a great matchup for his LM18 tunnel. But if you talk to Reid at BBC he will say that his 30hp on his LM works just fine.

Ryan there is more than just putting that 70HP Yamaha on the transom. You will have to add extra strength to the transom, add an extra layer of fiberglass to the bottom. I ran the 70 through my calculators and your top speed will be in the high 40's, speeds the LM18 was not designed for. Jacques recommends motor HP for a reason. Ask Jeff to ask Jacques for the specs to update the transom and bottom for the 70HP. You could get by with a 50 but that is all. For example, that same Yamaha 2st 70HP pushed my bigger OD18 to the mid 30's top speed with 500lbs of passengers on her. by adding the extra weight of the transom mods and fiberglass mods plus the extra weight of the 70HP you will not be able to get as shallow as the LM18 was designed for.

Tom

70 HP is a lot. It will be OK for the transom if you keep it running low but at WOT, the boat may be difficult to control. As some have said, the extra weight will bring the transom down and increase draft.
The recommended HP is 25 to 40. With a 40, the boat will plane with 3 persons and gear.

70hp will probably result in some major chine walk which will be terrifying and hopefully not toss you. Make sure you vest for sea trials. After experiencing the wot, you can always adjust the throttle down for safer operation.

Hey all! It’s been a long time, my daughters travel softball and work has kept me pretty wrapped up… knocking the dust off the boat this weekend to continue progress! My thought with the 70 and the tunnel was to go for a pretty aggressively cupped 4 blade for plane-ing out fast and running shallow long distances. If it becomes too much I’ll just sell the 70 and buy a 40 or 50.. I couldn’t pass on the deal at the time. I’m Definitely never going to run this boat wide open, as I never do my bay boat either.

I wouldn't even waste your time rigging it and putting it on. I mean strap on a. 100hp then. Aggressively cupped prop on a 70...you just don't need it with this boat. Buddy in town built one. With 3 guys and a 50 tohatsu..cav plate but no trim tabs he is on plane in 10ft. No bow rise. Jack foreman 3 blade.

That 70 is INSANE overkill my man. It's not about overpowered. it won't be running the right RPM range. It's heavier. A 50hp is overkill. A 70 is wayyyyyy outta of left field.

Jerid if he has a Yamaha 70 it weighs only weighs 6lbs more than a 50HP motor. As far as props he could run a triple cup 4-blade for max lift and then run in the 4000rpm range for cruising.

Tom

I would go 4 blade. It will give you lift, slows your top speed, handles better, and make you plane faster(which doesn't matter for this boat). My lm18 planes in about 3' of distance.

Been a long while since I’ve posted!

Definitely made some progress and most importantly learned a lot!

Hoping to get it to a point this week to flip back over for paint.

Nice work!!! Jeff

Here’s some more progress… Trying to burn through some resin and microspheres before I switch to the quick fair

Nice progress! Good idea to get the lockers painted while they were accessible. I see resin along the joint between the two foredeck panels, how did you support the joint?

Yes, nice progress!!! Jeff