343 Cobalt Outboard Open Bow Conversion
 

To not derail the great 343 cobalt information thread I thought it would be better to just start a new thread about this one off project.
So last year my wife and I started discussion what would be the perfect boat for us.

Here was our criteria
1) No wind for the operator/ passengers when running 50 to 70
2) Hard Top to be out of the sun
3) Outboards x 3 verado's for runs to the Bahama's and the keys
4) Full Bathroom
5) Rear facing lounger
6) Dual Row forward facing seating (Like a 390 nortech)
7) Sporty looking boat

I sketched a few concept drawings and my wife liked them so we now had a plan.
We happened to find one that was in OK condition with 494HO and Bravo XR's. We pulled and sold all of the inboard running gear and began cutting and cutting and cutting.
The last few months I have been rebuilding the transom, building the extend floor and finishing the fiberglass work on the open bow.
Here are a few pictures of where we are today. It should be ready for paint and interior by the end of July. The goal is to have it running by Oct.


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Holy Smokes!! This is an epic build!! What are you thinking for power?

Outstanding!

My only thought is the 200 gallon factory fuel capacity. Is that enough for triples?

Bold move, cutting up a perfectly good Cobalt but I like it. :)

I’ve always liked the Cobalt 343 and I’m an outboard fan. You and your wife have good tastes. :) Thanks for posting.

RR

I like it! Three-450s? :D :D :D :boat:

https://www.ram-trx.com/media/bold-s...jpg.24581/full

The plan for now is triple 300/350 I-6 verado's. 200 gallon should get us from Cape Coral to Marathon on 1 tank. As far as the 450's it would be cool but I have them on my 368 skater and they burn more fuel than the 400's they replaced. Also, I personally believe the I-6 verado's are more reliable and the V8 platform. And parts will be easier to come by if repairs are needed in the Bahamas/ keys. Time will tell if we made the right choice.

How about two of the new V10's? Lot's of torque for that heavy boat, close to the stock HP, and bigger gearcase to handle the load.

I have a budget for this build so any new engine is out of the question.
With 2 496's (850 total hp) the boat ran 66.
So with 3 x 350 = 1050 hp, Jack plates and about 1500lb weight reduction the boat should run 75 plus. Plenty fast for an island runner.

Cool project!

I see you are planning a hard top. Are you going to keep the speed top? I'd head over to cape coral within 24 hours to buy it if you want to sell it.

I will be using the lower section of the frame and adding a hard top to that.

looks great just curios what is the material you are using for the interior ( all the white ) also how much are you reinforcing the transom, knee braces, extra thickness to transom bracket? I would love to convert a 282 to twin outboards instead of buying a new outboard version at 300K Plus?

The new floor is made from Nidaplast Panels, very similar if not the same product as the factory floor and hatches.
https://www.boatbuildercentral.com/p...SABEgKdsfD_BwE

The transom required a lot of reinforcement, Now the transom is twice as thick as the factory I/O transom, I have built 5 knees and tied the bulkhead in front of the inboard motors to the transom by building 4 new stringers. These stringers also carry the load of the new floor. I will see if I have any pictures.

Yeah when you get a chance would love to see photos

Following this amazing build.... With the more recent move to OB's, I always thought the 343 would be a great candidate.

Took a factory tour at Cobalt a few years ago. Hinted to the folks there about an OB 343 and they just smiled, winked and said the molds are still out back. Lots of engineering & testing went into that single-step hull before they released it. The I/O's are a very predictable ride and solidly attach to the water.

Any progress update & photos?

I took the summer off from this project as this summer here in Florida was HOT! But, we are back at it. Modified the Stainless Steel support for the original cobalt top and I had this fiberglass hardtop made. I pick it up Saturday. I should be able to mount it next week.

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Here is what the boat will look like with the prototype wood top.

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Yeah no kidding on the hot I was just down in Bonita Checking on our Condo but keep it up

Picked up the Hardtop Saturday, here is the mockup on the boat. Needs the mounts welded to the frame and the holes drilled but I am happy the way it is turning out.
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Love the hardtop, it’s not full of wiring for 30 different colors of LCD lights, speakers, amps and sub-woofers.:)

Project is looking good.

RR

Amazing build!

Love it.

I like the thinking on power too.

Getting pts/svc in The Keys, let alone in the Islands, requires a large inventory of old motors and knowledge.

I built a powerhead for a customer in the islands who tried to get me to fly over to install it because he didn’t trust anyone over there!

And heard about the heat down there this summer!

When we lived down there and I was finishing my 24’ Sonic, weather was similar.

One day when doing final rigging, and knowing I would be up/down a ladder a bazillion times, I weighed myself before starting.

Ate we’ll, drank a ton of water (but never pee’d!) and weighed myself again, end of day.

Lost 9 lbs!

Ugh.

Amazing!!!

Any update? Are you bolting the egg beaters to the transom or using a bracket?

As of right now the boat is ready for paint/ interior and rigging but need to sell my Center Console boat to pay for this activity. I will be using 3 Bob's Jackplates with 10" setback when I install the engines.

Really dig everything about this project. I belive this is a conversion that will happen to many twin I/O boats in the future. Is your CC the 31 Active Thunder one in the OSO classified? If so, it's a tremendous value for the money and will be gone soon and then this project will continue to fascinate many of us. Can't wait to see this test run after first rigging.

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Yes, this is mine. Love the boat but wanted something with triples and a little bit different.

Did I miss where you reinforced the transom for loading of the OB’s?

Im a huge fan of the integral swim platform/brackets.

I always use the swim platforms and really like the additional floatation from the box/bracket and the side to side rigidity added by it.

Both of my twin OB 24’ Sonics had bowed transoms from lack there of.

I did not take too many pictures of that process, but I did reinforce the transom. The transom itself is now 4" thick, I added 3 knees, and then extended the stringers (4 of them) to span from the existing firewall (rear of old bench seat) to the transom.
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So I think you might be the right guy to ask this question, what is truly your opinion of the cobalt, the way they're put together, build quality, been thinking about getting one just don't know much about them, I understand the hardware they use seems to be better than others, I'm just wondering about the boat itself how it's put together, is the deck and hull fiberglass together? Thank you.

I can add my 02- with my 343 i have had over a yr now.
they are a pretty well-built boats. Little to no wood since early 2000s or so. I would say heaver than comparable sized craft too. So that should mean more structure.
My original interior is still in the boat being an 2005, I think they used better quality vinyl's or maybe mine was just better kept but the materials seem thicker.

I am sure Maritime can talk structure way better than I. But hitting wakes and such I hear very few rattles and such.
And most have 9'8" beam also so Fat Bottom Girls Rock. Now I Won't be wake Jumping like the Ciggy :ernaehrung004:
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I’ve always considered Cobalts to be near the top of the food chain for a production boat.

Always been i
pressed w/what I’ve seen.

And the transom looks great!

I have had two Cobalts in the past. For a mass production lake boat they are fantastic. Well built, well designed, and idiot proof. Back in the day when I did deliveries for the local Cobalt dealer I always showed new owners the "Cobalt turn". Full throttle and full lock turn at speed. Those things turned like ski boats. The only problem I had was the colored gel coat graphics. Cobalt was proud of the fact that the colors were in the gelcoat, but they would begin to fade almost instantly with any sun exposure.

Looking great as usual Don. I hope you and Amanda are doing well. I saw you picked up that 21 Shadow from the NE. Thanks again for thinking of me with the 24 Superboat. I needed a cabin. I found a Unicorn 23' Kryptonite with 300XS this summer. We need you to start a thread with all of the hulls you have customized over the years. You truly are an artist. Give Amanda my best. Bob

1st off I just want to say that I am by no means an expert in Fiberglass or the construction of boats. I have cut into a few over the years (Skater's, Doug Wright's, Fountain's and few others) and I will say I am very impressed they way this model of Cobalt is built. The above comments are correct that the structure of the boat is mostly wood free but the cabin area has wood in it.

Hi Bob, all is well here in Florida. Yep in the middle of rigging the 21 shadow (Amanda's boat she says) with a flashed 350 Verado. Should be on the water next week. A 23 Kryptonite is an amazing boat, enjoy. I have almost lost count on how many boats we have had in the last 15 years. LOL. Talk to you soon.

Status? The suspense of how it will sit in the water is killing me.

Subscribing to follow along, looking good, keep the pictures coming. I bought the Imco parts off this boat from you.

Well the last month has been busy on other projects. We just splashed my wife's boat and it runs really well. Now I will roll this one back out and start working on it. Can't do much until the CC sells. Really surprised it has not sold yet, maybe because of the holidays. We will see over the next couple of weeks. Merry Christmas to the cobalt family.
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That Shadow sure does look good on your prettier half. How does it run with 400 hp and what prop worked best for you? I have a new friend with a 23' Krypto like myself with the same power as your Shadow (flashed 350SCI to 400). He is at 85+ now looking to hit 90 with prop change. Merry warm Christmas to you both!

B

So just an update to the project. The Active Thunder officially sold over the weekend and the new owner took delivery. Now we are going to be moving on this project!
Does anyone have a good painter anywhere in Florida south of Orlando? I will need to have the bottom paint removed and then the entire boat painted Pear White.