We consider a dynamic positioning model of a surface vehicle, which is affected by bounded non-vanishing perturbation with non-zero mean. The main goal of this study is to estimate such model parameters with zero parametric error under the condition that the model is used in the closed loop and, therefore, the disturbance and regressor of the system are not independent. In order to achieve it, (i) the vessel model is parametrized into the perturbed linear regression form with both measurable regressor and regressand, (ii) a procedure of instrumental variables based dynamic regressor extension and mixing that has been recently proposed by the authors is applied. As a result, a set of scalar regression equations with respect to the vessel parameters with asymptotically vanishing perturbation is obtained, and consequently, such parameters are exactly identified in the asymptotic sense. Both simulation and experiment with a real surface vessel illustrate the presented theoretical result.