There are a total of 19 11-letter words containing 'boat', and the number may vary in different dictionaries. You can specify the dictionary and order.

• boatbuilder ₂₀
• dragonboats ₁₈
• houseboater ₁₇
• iceboatings ₂₀
• lifeboatman ₂₂
• lifeboatmen ₂₂
• motorboater ₁₇
• narrowboats ₁₈
• paddleboats ₂₀
• picketboats ₂₄
• sailboaters ₁₅
• sailboating ₁₈
• showboaters ₁₉
• showboating ₂₂
• bareboating ₁₆
• boatlifting ₁₇
• motorboated ₁₆
• powerboater ₁₈
• cockleboats ₂₁

There are 19 11-letter words containing boat in the well-known word game dictionary, 14 in the Scrabble US (US/Canada/Thailand - TWL/NWL) dictionary, and 13 in the Scrabble UK (International - SOWPODS/CSW) dictionary, and 14 in the Words with Friends (WWF) dictionary.