International Ultra 300 Hard Antifoul 2.5L Black

International Ultra 300 Hard Antifoul 2.5L is the ultimate hard antifouling for high‑speed powerboats and performance yachts operating in heavy fouling environments. Its durable formula maintains protection after hauling and allows scrubbing and polishing to reduce drag and preserve an ultra‑smooth hull.

Suitable for GRP, steel, wood and lead. Ultra 300 covers approximately 9 m² per litre; apply two coats for seasonal protection.

Available in Black, Blue, Navy, Red, White, Dark Grey and Green.

Ultra 300 replaces Interspeed Ultra 2.

Ultra 300 Key Features

• Ultimate hard formula for high‑speed boats and yachts operating in aggressive fouling areas.
• Up to 12 months protection in severe fouling conditions when applied correctly.
• Scrubbable and polishable to achieve an ultra‑smooth hull and maintain performance.
• Maintains protection after hauling so short periods ashore do not compromise effectiveness.
• Broad water compatibility: sea, fresh and brackish waters.
• Suitable substrates: GRP; Steel; Wood; Lead.
• High coverage: approx. 9 m² per litre.
• Colours: Black; Blue; Navy; Red; White; Dark Grey; Green.
• Replacement: direct replacement for Interspeed Ultra 2 for easy cross‑reference.

 

Technical specifications

• Pack size: 2.5 L
• Coverage: 9 m²/Ltr
• Recommended coats: 2
• Touch dry: 1 hr at 5 °C; 45 mins at 15 °C
• Minimum immersion time: 24 hrs at 5 °C; 12 hrs at 15 °C
• Maximum effective immersion time: 12 months depending on fouling pressure
• Thinners: No.3
• Suitable for: Powerboats, fast yachts, and vessels requiring a hard, durable antifoul

Ultra 300 is the replacment for Interspeed Ultra 2

Download International Ultra 300 Product Data Sheet here.

Download International Paint Colour Chart here.

Download International Paint Manual here.

Overcoating a different type or brand of antifoul? See our antifouling compatibility chart here.

Application guidance and best practice

• Surface preparation: Remove heavy fouling, degrease, and abrade glossy surfaces to ensure adhesion. Treat bare steel and wood with appropriate primers.
• Coating: Apply two even coats; ensure recommended film thickness for full season performance. Allow specified touch‑dry times between coats.
• Maintenance: Can be polished after curing for reduced drag; in‑water scrubbing permitted for light fouling maintenance. Avoid over‑abrasion that removes the working film.
• Haul out and relaunch: Product maintains protection after short haul outs; re‑inspect and touch up if extended time ashore occurs.
• Safety and cleanup: Use suitable PPE, follow local waste disposal regulations and use Thinner No.3 for cleaning equipment.

Royal Mail Service Update: Please be aware when choosing Royal Mail as your preferred delivery method, your delivery time may be impacted by ongoing strikes and may take up to 20 working days. If your order is time critical we suggest choosing a courier or Next Day Service

 

Our Mail Order team ship chandlery, yacht parts and sailing clothing around the world. We use the best value couriers available, and we will endeavour to get your products to you as quickly and as cost effectively as possible.

International Orders: Due to delays we have had to suspend our international delivery options. 

UK Standard Delivery

• UK Mainland 0 - 2Kg (small jiffy) £3.95 Royal Mail Service. Despatch within 3- 5 working days, delivery in 7-10 working days for orders under £100.00. This is an estimated delivery window from our chosen courier.
• UK Mainland 0 - 30KG £5.95 Courier service with signature. Despatch within 3- 5 working days, delivery in 7-10 working days. This is an estimated delivery window from our chosen courier.
• UK Mainland 0 - 30KG OVER 1.2m LENGTH £15.95 Courier service with signature. Despatch within 3- 5 working days, delivery in 7-10 working days. This is an estimated delivery window from our chosen courier.
• UK Mainland 30KG+ Price on request
• UK Mainland Next Day 0 - 30KG £9.95 Courier service with signature, orders must be placed before midday. This is an estimated delivery window from our chosen courier.
• UK Mainland Next Day 0 - 30KG OVER 1.2m length £19.95 Courier service with signature, orders must be placed before midday. This is an estimated delivery window from our chosen courier.
• UK Mainland Saturday 0 - 30KG £19.95 Courier service with signature, orders must be placed before Friday. This is an estimated delivery window from our chosen courier.
• Northern Ireland, Highlands & Islands 0 - 2KG (small jiffy) £3.95 Royal Mail Service. Despatch within 3- 5 working days, delivery in 7-10 working days for orders under £100.00. This is an estimated delivery window from our chosen courier.
• Northern Ireland, Highlands & Islands 1 - 30KG £10.95-£14.95 Courier service with signature. Despatch within 3- 5 working days, delivery in 7-10 working days
• Northern Ireland, Highlands & Islands 1 - 30KG OVER 1.2m length  from £24.95 Courier service with signature. Despatch within 3- 5 working days, delivery in 7-10 working days
• Northern Ireland, Highlands & Islands 30KG+ Price on request
• Channel Islands 0 - 2KG (small jiffy) £5.95 Royal Mail Service Despatch within 3- 5 working days, delivery in 7-10 working days for orders under £50.00
• Channel Islands 1 - 30KG £19.95 Courier service with signature. Despatch within 3- 5 working days, delivery in 7-10 working days
• Channel Islands 30KG+ Price on request

UK Exceptional Delivery

• UK Mainland; Antifoul & paints £5.95
• UK Mainland; Inflatable dinghy £10.00
• UK Mainland; Liferafts £17.50
• UK Mainland; Flares £49.95
• Northern Ireland, Highlands & Islands; Antifoul & paints £9.95
• Northern Ireland, Highlands & Islands; Inflatable dinghy price on request
• Northern Ireland, Highlands & Islands; Liferafts price on request
• Northern Ireland, Highlands & Islands; Flares not available to ship at this time
• Channel Islands; Antifoul & paints £13.50
• Channel Islands; Inflatable dinghy price on request Channel Islands; Flares not available to ship at this time

Ship to Store service; You can now order from our website for collection from one of our 9 Force 4 locations. Simply select “Ship to Store” at checkout and your goods will be ready for collection within 5 working days. This service is free however may exclude some hazardous or special order goods.

For further delivery information click here.

Standard Returns

If you are not entirely happy with your purchase, we will exchange or refund your goods in full, provided that the items are returned within 14 days of receipt.*

Please check the condition of goods on arrival - we are unable to accept goods damaged during shipping after 14 days.

Returned goods must be packaged securely, with all original packaging undamaged and in a saleable condition i.e. shoe boxes must be in the same condition as when received.

Goods must be unused and security seals intact.*

If you would like to return goods because they were ordered incorrectly or if clothing does not fit, return postage will be at your expense. If you would like us to replace the goods with another size or colour, we will charge carriage on the replacement.

Please be aware that some navigational and safety products may be dated, and as such a full refund may in some cases not be possible. If you are purchasing dated navigational charts we suggest you contact us for more information.

Faulty Goods

If you receive your goods and believe them to be faulty, please contact us straight away with a brief description of the problem. If we require you to return the product for a replacement, we will send you a pre-paid Royal Mail label for delivery back to us. Unfortuantely we cannot send the courier back to collect the items.

Returning goods to Force 4 is easy!

1. Please contact us by ringing 0345 1300 710 or email on [email protected]. This way we'll be able to determine whether you would like to return the product for a refund or whether you'd like to exchange the product. We are unable to process the return of faulty goods that we're not expecting.
2. We'll then give you a returns number. This returns number will need to be clearly marked on the outside of your parcel so it can be identified on arrival. Please note, failure to mark a returns reference number on the outside of your parcel may result in a delay in processing your return.
3. Don't forget your proof of postage, just in case!
4. Once we receive the item we'll be able to proceed with a refund or an exchange.

*this excludes faulty goods with manufacturers defects. If goods are found to be faulty during use, after the returns period, please just give us a ring on 0345 1300 710 and we'll be happy to help.