Details of the deal have not been disclosed but YFM looks to invest up to £10m in fast-growing UK companies.
Gill was established in the 1975 by Nick Gill who started up the business in his father's Nottingham lace factory.
The business, which makes technical sailing clothing and accessories, generated sales of £11.2m in the year to 30 September 2012 – the latest accounts available on Companies House – and a pre-tax profit of £1.4m. It now exports to more than 35 countries and last year won the Queen's Award for Enterprise for International Trade. Gill employs more than 40 staff at its Long Eaton site.
As part of the deal, Steve Richards will be joining Gill as non-executive chairman. He is currently chairman at QualitySolicitors and Waterbabies and was previously chief executive of Interflora and managing director of Manchester United Merchandising.
The management team includes managing director John Deverill, who has been with Gill for 16 years, sales director Bryan Stewart and product director Matt Clark.
Nick Gill will be a non-executive director in the company after the transaction with YFM.
YFM director Paul Cannings said: "This is a strong management team that has delivered growth for the past three years in a difficult retail market. With our financial and strategic support we will help the team develop the brand further and increase its market share in existing and newer markets."
Gill managing director John Deverill added: "It has been a great pleasure to work with Nick and the team as we developed Gill into a premier international brand of sailing apparel. With Steve, Bryan, Matt and the team at YFM Equity Partners we are excited by the opportunity to continue to develop and invest in the brand and increase our international market share."
Clearwater Corporate Finance led the deal. Yorkshire Bank provided debt funding and working capital facilities to support the deal.
The acquisition finance team at Yorkshire Bank in the Midlands, led by directors Ian Howey and Ian Mansell, provided debt finance. Ian Waterfield and Paul Cannings were the YFM Equity Partners deal team.
Phil Burns, Gareth Iley and Sebastian Saywood of Clearwater Corporate Finance advised the shareholders on the deal; Grant Thornton provided financial due diligence; and legal advice came from Osborne Clarke.
Nelsons provided legal advice to the vendors, Fraser Brown advised the management team and Gately advised Yorkshire Bank. Tax advice was provided by RSM Tenon.