First Aluminium Boat Building Advice, 18ft

Hello everyone,

Thanks for entering to this post.

I´ve been on the water since I was 5 yo. My dad had several fiberglass fishing boats all between 16 and 18 ft.

I live in Buenos Aires, Argentina and here we have the Parana Delta. More than a thousand small rivers and a few wide ones specially Rio de la Plata between Argentina and Uruguay that´s a estuary and can have really choppy waters up to 5 ft height but normally is 1 to 2 ft.


Above Normal conditions Rio de la Plata

That estuary where we fish has a lot of banks and shallow waters best fishing spots have passages of 2ft draft like the next pic.


Dorado sportfishing in summer


Ok so many words sorry, the point is here we don´t have aluminium boats and I think will be perfect for that purpose the rivers are sediment colour full of submerged tree branches and trunks. I have repaired the hull a million times.

I would like to build an aluminium boat 18ft for using with one 60 hp Yamaha 2 stroke. We will be max 4 people fishing. Lately we been fishing in a 16ft fiberglass boat powered by a Suzuki 40hp 2 stroke 4 people cruising speed was 19mph. I hope to reach 25 mph cruising and 35 mph max speed. I will try to build it strong but simple keeping the design the lighter I can.

Don´t know if building a catamaran would be more difficult and expensive. But I really like the point that sometimes we fish on the same side ( not the 4 of us ) and for shallow waters the catamarans are better. Also I can have a nice spacious beam.

I have seen many plans and ideas like this.

Plate Alloy Australia - Catamarans http://www.platealloy.com/cats.htm

- Boden Boat Plans https://www.bodenboatplans.com/index.php?cPath=1

And ideas in mind like these ones.


Tideline 190cc (I know is fiberglass made)

Tideline 190 CC Power Cat: A Great Boat for Northeast Waters | New England Boating & Fishing https://newenglandboating.com/tideline-190-cc-power-cat-a-great-boat-for-northeast-waters/


Kingfisher 510 Minicat


520 Webster Twinfisher


Any comments and advice are more than welcome. And of course invited for the next fishing trip ( I hope soon)

 

Welcome to the Forum Ozmy.
That is a very impressive Dorado in your first photo!

It sounds like an aluminium boat would be a good choice of fishing vessel, especially re the good possibility of encountering submerged tree trunks and branches.
And many on here (myself included) would be in favour of a catamaran over a monohull generally.
Although if you are going to have a catamaran, it might be better to have twin outboard motors if the budget will allow for this.

In view of how there is so much floating rubbish in your river, it would be worthwhile selecting a design which has some form of protection for the propeller(s), perhaps in the form of a skeg / keel on the underside of the hull(s).

Mr Efficiency on this Forum is very experienced re small power cats, and he will be able to give you some good advice.

Do you intend to build the boat yourselves, or contract out the aluminium fabrication and welding work?

 

Have you checked aluminum flats boats? They operate in choppy shallow waters. I am well familiar with the conditions you fish in. The waves are short and steep.

 

Thanks for your reply , I will do it myself . I have welding experience and technical experience (not in boat building)

About the keel or protection I think it will add draft to the boat and about the dirt in the river you know **** happens (not all the time) but normally first it hits the bow. One thought was doing a kind of Jet Jon but donor PWCs are really expensive here and attaching it to the hull will be a extra job and will take space onboard.

 

Thx for you reply , I will take a look . Any brand or model to recommend?

 

Just saw this one .

2020 Alumacraft 18 BAY http://www.alumacraft.com/Alumacraft-Boat.php?id=653

Looks that fits my needs , of course my result will be much rougher jeje. Also I saw this one 2020 L1852MT Jon Fishing, Hunting and Duck Hunting Boats | Lowe Boats https://www.loweboats.com/jon-boats/l1852mt-jon/ but I think these boats in mild choppy waters will be a pain in the ... at least they should have a moderated V hull finishing almost flat to the stern. But I like the idea indeed.

You think wolud be easier to build than a same lenght cat ? At first sight it looks like.

 

Hey I found the perfect hull shape Alumacraft Boat Co. https://www.youtube.com/user/alumacraftboatco/featured

 

Excellent! Which of the boats on their site do you like the most?
Alumacraft Boats: Aluminum fishing boats, Jon Boats and Bass Boats for sale http://alumacraft.com/

Re the video, I must admit to being slightly dubious about how the hull is 2 skins, riveted together - but I guess it must have worked for thousands of boats already.

 

Hello OZMY, is the requirement that the power be a single 60hp Yamaha, flexible ? That isn't sufficient power for an 18 foot boat that will handle choppy conditions well. Shown below is a link to plans for cats, they are a bit dated, but the lines seem OK. Very cheap ! Two engines, though. And cats are a much bigger project than a monohull, so many more panels. Oh, and the golden fish, are they good eating ? Not surprising it too got the name "dorado", it is similar in hue to the oceanic Dorado (Mahi-Mahi)
BoatPlans.com http://www.boatplans.com/cgi-local/shop.pl?cart_id=53f74bf9512f4bf1e954a01eaf4e8ac6&type=item&categ=023&item=1105800411

 

Re the Boat Plan link above, US$59 for a set of plans for a 17' aluminium power cat would be money well spent I think (even if just for general reference re construction details) if you are serious about possibly building a cat.
As Mr E says it would be a lot more work, but for the sea conditions that you describe (re what it will have to put up with) a cat would cope much better than a Jon Boat or similar.
It might even be feasible to weld on a skeg on each hull to help to protect the legs of the O/B motors from all the submerged tree trunks that are lurking unseen.
Although by doing this you would probably lose a few knots of top speed.

 

Sorry it seems I didn't paste the URL correctly.

The hull type is this one



The model I like can be this one

2020 Alumacraft Edge 175 Sport http://www.alumacraft.com/Alumacraft-Boat.php?id=696

Also I saw some Ranger boats the VX 1788 can be an inspiration.


Re the video, I must admit to being slightly dubious about how the hull is 2 skins, riveted together - but I guess it must have worked for thousands of boats already.

 

Thx for the reply Mr. E

The Yammie 60hp is the outboard I have , a new 115hp 4 stroke is well above 10k here. The regular fishing boat here is a Panga flat bottom fiberglass 18ft to 20ft with a 50/70hp.

About the Dorado is an amazing catch, so sporty it jumps out of the water and fights bravely. Also is delicious. Normally we keep one and give back the rest.

Will check the plans now.

Thx a lot.

 

I love Cats hope to have one Freeman one day jeje. My fishing day budget can't handle two engines and 15k minimum in outboards is a lot.

I'll take a look to the plans above.

Thx Bajansailor

 

Thank you gentlemen !

The Stormcat of the plans is quite similar to the Noosa cat - Twin fisher. I like that one.

If I get another Yammie fot the other hull... Ummm don't tell my wife the idea Jaja.

What's really serious here is the gasoline price 1 dollar/litre that's almost 4 dollars per gallon. Crazy!!

I guess twin 60hp outboards on that hull average sailing conditions, 4 people + gear will burn 25/30 liters/hour cruising speed 35mph. Just ask my crystal ball.

Average journey is a 4 hours run so 120 bucks for sure. Did I tell you here the minimum monthly wage is 200 dollars.

Don't cry for me Argentina....

 

For what you want to do these designs are better, you can build them much easier.

Alumaweld.com