Aluminum Plate for Fishing Boat: Grades, Tempers & Plate Sizes Explained
Fishing boats work harder than almost any other vessel. They sit in saltwater 24/7, get knocked around by nets and ice, and lose 10–15% of their resale value if a single hull plate corrodes through. The aluminum you choose today decides whether the boat is still earning money 15 years from now. In this guide, we break down the alloys, tempers, thicknesses, and panel sizes used for fishing boat hulls, decks, and superstructures. We will help you match the right marine-grade aluminum plate to your vessel size, so you can buy with confidence.
- Why Aluminum Is the #1 Material for Fishing Boats
- Six Real Advantages for Commercial Fishermen
- Main Aluminum Alloys for Fishing Boats
- Small Fishing Boats (5052 & 6061)
- Medium Fishing Boats (5083 & 5086)
- Structural Extrusions: 6061 & 6063
- Specification of Marine Aluminum Plate for Fishing Boat
- Choosing the Right Plate for Each Hull Part
- Certifications & Mill Standards
- People Also Ask
- Related Product
- Request a Free Quote
1. Why Aluminum Is the #1 Material for Fishing Boats
Modern fishing fleets have moved decisively from fiberglass and wood to aluminum. The reason is simple economics: aluminum hulls last longer, weigh less, and recover more value at end of life. Three factors explain the shift:
- Fuel economy — aluminum hulls weigh 15–20% less than steel, so they burn less fuel per nautical mile.
- Service life — an aluminum fishing boat typically lasts 10 times longer than a fiberglass boat under the same operating conditions.
- Repairability — damaged plates can be cut out and welded in within hours; the repaired section is as strong as the original.
For commercial operators, those three factors combine into one thing: lower total cost of ownership.
2. Main Aluminum Alloys for Fishing Boats
Five alloys cover virtually every fishing boat on the water today. Choosing between them comes down to hull size, construction method (riveted vs. welded), and part of the boat.
| Alloy | Construction Method | Hull Size | Key Property | Common Temper |
|---|---|---|---|---|
| 5052 | Riveted or welded | Small (≤ 8 m) | Excellent formability, low weight | H32, H34, H112 |
| 5083 | Welded (most popular) | Medium to large (8–30 m) | Highest strength among 5xxx | H116, H321, H112 |
| 5086 | Welded | Large (15–35 m) | Top weldability, marine-grade | H32, H116, H321 |
| 6061 | Riveted (rarely welded) | Structural members | Heat-treatable, structural | T6, T651 |
| 6063 | Extrusions | Trim, rails, channels | Easy extrusion, smooth finish | T5, T6 |
3. Small Fishing Boats (5052 & 6061)
For dinghies, skiffs, and small outboard-powered fishing boats under 8 meters, the dominant choices are 5052-H32 and 6061-T6. 5052-H32 / 5052-H34 is the workhorse of small craft. It forms easily around chines and gunwales, welds cleanly, and weighs about 7 kg/m² at 4 mm thickness. Many production skiffs use 0.25-inch (6.35 mm) 5052-H32 for the hull and 3 mm 5052 for the inner liner. 6061-T6 is used where you need higher strength — typically the transom, console supports, and tiller brackets. Its downside is poor weldability; most small fishing boats use 6061 only in riveted form or in extrusions.
4. Medium Fishing Boats (5083 & 5086)
Once a fishing boat passes 8 meters and starts working offshore, 5083 takes over. Its 4.0–4.9% magnesium content gives it about 30% more strength than 5052, with no penalty in corrosion resistance. 5083-H116 / 5083-H321 in 5–8 mm thickness is the typical hull plate for 12–25 m purse seiners, trawlers, and longliners. The boat in your harbor was almost certainly built from it. 5086-H32 is the alternative for very large welded hulls (15 m+). It is slightly more expensive than 5083, but it welds even more cleanly — important when you are stitching together long panels for a 30-meter hull. The most popular temper for hull plating is 5086-H32, in thicknesses of 0.45 to 12.7 mm.
5. Structural Extrusions: 6061 & 6063
No fishing boat is made of plate alone. You also need extruded shapes for:
- Keels and chines
- Gunwales and spray rails
- Cabin frames and stringers
- Masts, outriggers, and booms
The two extrusion alloys used are:
- 6061-T6 — for heavy structural members like keel stems and mast tubes.
- 6063-T5 / 6063-T6 — for decorative and lightweight structural sections; it extrudes with a smoother surface finish.
For in-house plate supply, the most common fishing boat product mix is 5083 plate + 5052 plate + 6061/6063 extrusions.
6. Specification of Marine Aluminum Plate for Fishing Boat
The table below shows the standard specification supplies for fishing boat builders. It is compatible with the major marine classification society rules.
| Alloy | Temper | Thickness (mm) | Width (mm) | Length (mm) |
|---|---|---|---|---|
| 5052 | F, O, H12, H14, H16, H18, H19, H22, H24, H26, H28, H32, H34, H36, H38, H111, H112, H114 | 3 – 50 | 20 – 2650 | 500 – 16000 |
| 5083 | O, H12, H14, H16, H18, H19, H22, H24, H26, H28, H32, H34, H36, H38, H111, H112, H114, H116, H321 | 3 – 50 | 20 – 2600 | 500 – 16000 |
| 5086 | O, H111, H112, H116, H321 | 3 – 50 | ≤ 3600 | 500 – 16000 |
| 6061 | F, O, T4, T6, T651 | 3 – 50 | 500 – 2800 | 500 – 16000 |
| 6063 | T5, T6 | 3 – 50 | ≤ 700 | 500 – 16000 |
7. Choosing the Right Plate for Each Hull Part
A fishing boat is not built from a single alloy. Each part has different stress, weld, and corrosion requirements. The table below recommends allocating alloys by hull zone.
| Hull Zone | Stress Level | Recommended Alloy & Temper | Typical Thickness |
|---|---|---|---|
| Bottom plate (below waterline) | Very high | 5083-H116 / 5086-H116 | 6 – 10 mm |
| Side shell plate | High | 5083-H116 / 5083-H112 | 5 – 8 mm |
| Deck plate (tread) | Medium | 5052-H32 / 5083-H116 | 4 – 6 mm |
| Bulkhead & superstructure | Medium | 5052-H32 / 5083-H112 | 3 – 5 mm |
| Wheelhouse & mast | Structural | 6061-T6 (extrusions) | Custom profile |
| Keel & chines | Very high | 5083-H116 extrusions | Custom profile |
| Internal tanks (water, fuel) | Medium | 5052-H32 / 5083-H112 | 3 – 5 mm |
| Decorative trim | Low | 6063-T5 / 6063-T6 | Custom profile |
8. Certifications & Mill Standards
For a fishing boat that operates commercially, you need aluminum plate that meets classification society rules.
- DNV — Det Norske Veritas (preferred for European fleets)
Mill test certificates are issued by the producing mill, per batch. Plate production complies with ASTM B209 and EN 485.
9. People Also Ask
Which aluminum alloy is most popular for fishing boat hulls?
For welded fishing boats over 8 m, 5083-H116 is the most popular alloy globally. It combines high strength (tensile ~ 305 MPa), excellent seawater corrosion resistance, and clean weldability. For small riveted skiffs, 5052-H32 is more common because it forms more easily.
What thickness of aluminum plate do I need for a fishing boat hull?
As a rule of thumb: 4 mm for small craft under 6 m, 5 mm for 6–10 m boats, 6 mm for 10–15 m boats, 8 mm or more for boats over 15 m or operating in heavy seas. Bottom plates should be 1–2 mm thicker than side shell plates in the same vessel.
Can I weld 5052 aluminum plate on a fishing boat?
Yes. 5052 welds very well with 5356 filler wire using MIG or TIG. The welded joint will be slightly stronger than the parent metal. Use 4043 filler if you need a smoother bead appearance, but expect a small strength penalty.
What is the difference between 5083-H116 and 5083-H321?
Both are marine tempers for 5xxx alloys above 3% magnesium. H116 is strain-hardened and stabilized for seawater service. H321 is a low-temperature stabilized variant of H116 with slightly better formability for complex curves. Both are accepted for fishing boat hulls; H321 is often specified by DNV-certified yards.
How long does an aluminum fishing boat last?
A well-maintained aluminum fishing boat typically lasts 25 to 30 years. The hull rarely fails — most boats are retired because the engine, electronics, or refrigeration system becomes obsolete, not because the aluminum has corroded.
Is an aluminum fishing boat more expensive than fiberglass?
Yes — the upfront cost is typically 20–40% higher than a comparable fiberglass boat. However, the total cost of ownership is lower because the aluminum boat lasts 3–4 times longer, repairs faster, retains resale value, and uses less fuel due to lower weight.
Can I use aluminum plate from any supplier for a fishing boat?
Technically yes, but for a commercial fishing boat you should insist on a DNV-recognised marine grade with a mill test certificate issued by the producing mill for your batch. Uncertified plate may have inconsistent chemistry or mechanical properties, which can lead to early cracking or corrosion.
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About Delin Aluminum
Delin Aluminum has supplied 5083, 5086, and 5754 plate and sheet in H116/H321 tempers for over 10 years. Our partner mills hold DNV certification — the approval most marine buyers require — with other major classification societies available on request.
