18.5' Specmar Aluminum Landing Craft - Not A Build Thread

Questions about boat repairs with our resins and fiberglass: hull patches, transoms and stringers, foam, rot etc.
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Netpackrat
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18.5' Specmar Aluminum Landing Craft - Not A Build Thread

Post by Netpackrat »

So yeah, as I mentioned elsewhere, I pulled the trigger on this build, and had all of the kit parts CNC cut by Alaska Copper and Brass, and then shipped up to Anchorage. This isn't going to be a "normal" build thread documenting everything that goes into the build... I have enough to do as it is, without trying to keep something like that updated. What I am going to do instead, is just post occasional pictures here, and probably lots of questions related to boat systems in general, but not really the process of building the hull itself. That's because while I grew up in a small coastal fishing community (pop ~2500), where boats, fishing, and seamanship are a way of life, I am primarily a landlubber. Most of my boating experience is with canoes, and small skiffs on small rivers and lakes. As a 20+ year A&P mechanic I am not completely clueless, and my dad owned a 1970s Bayliner with twin Chrysler 360s that spent very little time in the water and a lot of time being worked on. Much of that time had me crammed into some tight spot that my dad couldn't get into working on it. But I don't fundamentally know a lot about boat specific mechanical or electrical systems. I do have the books my dad bought on those subjects, which are probably hopelessly out of date now, being from the early 90s.

Anyway, this isn't my first boat build, and it's far from my first metal fabrication project. But it is my first metal boat project. I've previously done some welding of aluminum, but that was almost all TIG of very light material (.050"-.060"). I am pretty new to the MIG welding of this heavy gauge aluminum. I am using an HTP Revolution 2500 multiprocess welder. I am currently using the standard 9' graphite lined whip and mig gun that it ships with for welding aluminum, but I am planning on buying a spool gun with a 25' whip soon, as constantly moving the power supply around the boat to reach where I am welding is a PITA.

https://www.specmar.com/aluminum-boat-p ... raft-1520/

This is the boat. The picture at the above link sucks, but there is a pdf drawing which is more useful. I can't find on any of the drawings they sent where an empty hull weight is given, but the weight of the raw aluminum prior to cutting (so, including the pallet of scrap that shipped with it, plus whatever the router removed as kerf) was just over 2500 pounds. So not more than that for hull weight, and they seem to indicate that the weight of the boat with systems, the 130hp Honda they show, and full fuel is 2880 pounds. Max displacement is 3880 pounds. So give or take 1000 pounds of cargo and passengers, depending on what motor I choose.

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They don't call for a jig due to the accuracy of the CNC cut parts; rather they just say build it across 4x4s leveled on the shop floor. In order to be able to move it around a little bit, and to create a better working height (we'll see if I still think it's better after I get the sides on), I made a frame out of 2x10 lumber,and leveled my 4x4s across that. It's sitting on 4 chinese made machine skates (allegedly 6000# capacity each) that I bought for moving my big shear (which is great for aircraft material, but alas too light duty to be of use on this project).

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This was a little frightening. .190" (3/16) aluminum doesn't really like to bend like this, and several ratchet straps gave their lives forcing the shape into the bottom panels. I am currently welding stringers into this area, treating it with caution since I had tacks "unzip" on me several times while putting these into shape. I probably won't relax working on this until after I get the ribs and the chines tacked in place.

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Keel, "ski" (pad, etc), transom, bottoms, and the first longitudinal stringers tacked in place. With my aviation background, I keep referring to the stringers as "longerons" which has confused the hell out of my more boaty friends when I have talked to them about the project.

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How it sits presently. The frames are not tacked in; I am just using them to help in aligning the remaining stringers. Once those and the forward girders are in place, then I can start tacking in the frames.

Anyway, probably the real purpose of this post is to solicit feedback on choices for motor, trailer, etc. since there will be a lead time for those items. I probably need to order a trailer soon if I want it here this summer. I could build my own but I have my hands full already building the hull. I have been relatively happy with the EZ Loader that I bought for my jon boat, so I was thinking of one of their tandem axle units meant for a 4000# boat (so about 5K gross weight). The goal is to be able to drop the bow door and load up in my driveway using ramps (for loading my quad, etc). It may be desirable to build a little extra weight capacity in, but the models I am seeing with heavier capacities are also meant for longer boats. I'm open to suggestions... Trailering distance is about 170 miles from my house to the boat launch, up and down several mountains. So durability and capacity are important, but extra weight is just that. Current tow vehicle is a 2017 crew cab half ton ram with the hemi V8, but I may want to occasionally tow it with the wife's Durango which IIRC has just over 6000# max tow weight.

I have bounced around a bit on the motor. When I first began considering this boat, I was thinking just a regular 80hp outboard to stay within the design limit for tiller steering, to keep it simple as possible. After a season traversing the lakes to and from my property with the jon boat and a prop outboard, it became obvious that I need a jet unit because both the approach to my property and the channel between 2 lakes that I have to transit are very shallow, and there's lots of other shallow spots too. I had just about talked myself into a 115hp jet outboard (which with the jet loss gives 80hp at the pump, and thus meets the design limit for tiller steering). But after more thinking, and seeing the size of the boat coming together, I am leaning more towards a 150hp jet (so about 105 at the pump), and hoping that will be enough. There's a jump of about 100 pounds motor weight going to the 150 so for the extra 25hp at the pump I'd lose 100# of cargo capacity. I don't really care about top speed that much; 95+% of the time I will be crossing the same two freshwater lakes the approximately 15 miles from the boat launch to my property. Probably with the occasional run on a river for moose hunting, and maybe once in a while in saltwater for halibut or deer hunting on the islands out in the sound. But mostly it will be back and forth on the lakes.

If I were ordering a motor right now, I would pick Yamaha's 150 jet. I asked my friend who used to work at the outboard shop in our hometown if he recommended Yamaha or Mercury (they both make a 150/105 jet), and he said between those two, Yamaha all day, every day. The local Yamaha dealer is also the EZ loader dealer so I may be able to get a better deal if I buy both the trailer and the motor from him. Mercury support in Anchorage seems spotty... There's the Bass Pro, and one shop down on Old Seward that usually has overpriced boats for sale on Craigslist. Vs the Yamaha dealer that I have already bought a jon boat and trailer from. But I am open to ideas.

I did look into buying a prop outboard and one of the jet conversion units, but those all appear to have a 6+ month lead time on orders. That would open up the option of a Suzuki outboard.... They seem to be a good deal, but they don't appear to offer a factory jet. The local choices for used motors don't appear to be great either. Anyway, thanks for reading this far.

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cape man
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Re: 18.5' Specmar Aluminum Landing Craft - Not A Build Thread

Post by cape man »

Yamaha all day, every day. I'll never switch brands due to performance, service and parts availability.
The world always seems brighter when you've just made something that wasn't there before - Neil Gaiman

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Re: 18.5' Specmar Aluminum Landing Craft - Not A Build Thread

Post by Fuzz »

I think all the big manufacturers all build good stuff now days. So I would make my chose based on the dealer. Down here that means Suzuki but it would be different in other areas. As for power I have yet to hear anyone complain they had too much power. The extra cost for more power is cheap compared to wishing you had more all the time.
For the trailer make sure you add its weight into the rating to make sure you have enough trailer. I would bet 90% of boat trailers are running around overloaded.

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Re: 18.5' Specmar Aluminum Landing Craft - Not A Build Thread

Post by fallguy1000 »

The only place with better after purchase customer support for anything you buy than Yamaha is Seastar steering.

I ordered something out of the catalog at a Yamaha dealer and the part number was not the right part to order. It was like $790. The dealer refused to accept the item as a return because ‘it was electrical’. I told them, we’ll see. I explained, in detail, the issues to Yamaha OB support and they agreed and told the dealer to refund my money for the part. Imagine getting a phone call from the dealer explaining Yamaha has ordered them to do the return, so please bring us the part after being told to pound sand by that same dealer.

But this was not all. My boat is super complex to setup. Yamaha helped me on all, but one part of the integration to Glendinning controls. And they did not have to do it. Their dealer network and specifically, Andrew at Sim Yamaha on Washington Island, Wisconsin were also helpful. My boat could not be rigged by a Yammie dealer because the boat was too big to take to the dealer, so they helped me bigtime.
My boat build is here -------->

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Re: 18.5' Specmar Aluminum Landing Craft - Not A Build Thread

Post by Netpackrat »

Thanks for the input guys, especially for the Yamaha vote of confidence.

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Re: 18.5' Specmar Aluminum Landing Craft - Not A Build Thread

Post by Netpackrat »

Image

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Re: 18.5' Specmar Aluminum Landing Craft - Not A Build Thread

Post by cape man »

Looks like a LOT of welds to me!! Build on!
The world always seems brighter when you've just made something that wasn't there before - Neil Gaiman

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Re: 18.5' Specmar Aluminum Landing Craft - Not A Build Thread

Post by Netpackrat »

Yeah a lot of welding. I got my spool gun with the 25' lead set up the other night so I won't be having to move the machine around so much. The first place that was recommended by my friend wasn't confident he could bend my formed parts with the degree of accuracy needed, but he pointed me at another place out in Palmer who was able to do all the bends on his press brake, although the two bow corners were too big for his roller. So I need to either find a shop that can do those, or take them back to the guy in Palmer and have him do it with a series of small bends on the press brake, although I'd rather get them rolled. He had some landing crafts under construction in his shop, all with squared bow corners which still looked fine and would have been easier, but what I have is what I have. He also has a big CNC table and probably could have cut my kit, although he couldn't have marked the lines like Ak Copper and Brass did. Something to keep in mind for future projects though.

He also gave me some more outboard info. Mercury is back in the running because according to him, I can get a jet bigger than 150 with most of the manufacturers, but with all of them but Mercury, the lead time is long since all of the jet units are made by the same company which has a long backlog. Except for Mercury who supposedly makes their own jet lower units, and I may be able to get the prop lower unit as part of the package, which would be useful if I take it out in saltwater much. Thinking about a 175, which would be the max it is rated for with the prop, and would give 120+ with a jet, so pretty close to the 130hp that Specmar shows on the drawings and what is pictured in the photo on their site. And I just learned there is a boat show this week here in Anchorage, so if I can manage to drag myself to that, it might be a good opportunity to shop for a motor and a trailer.

Last week my brother came over and helped me move the sides off the trailer and into the shop. They are .160" 5052 and too heavy for me to move, so they'd stayed on the pallet since December. Scratched my head for a while figuring how to lift and hold them in place for tacking, and last night I finally made a couple frames out of 2x4s which let me hoist them up using ratchet straps. I have about the aft 6' of the starboard side tacked in at this point. Need to go get a couple sheets of plywood to lay across the tops of the frames, so I can get inside to tack the sides to the ribs, plus I need to get my big argon tank exchanged since I am down to about 600psi on my smaller one now.

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