A search for scalar top quarks in R-parity violating supersymmetry is performed in e+p collisions at HERA using the H1 detector. The data, taken at and 301 GeV, correspond to an integrated luminosity of . The resonant production of scalar top quarks in positron quark fusion via an R-parity violating Yukawa coupling λ′ is considered with the subsequent bosonic stop decay . The R-parity violating decay of the sbottom quark and leptonic and hadronic W decays are considered. No evidence for stop production is found in the search for bosonic stop decays nor in a search for the direct R-parity violating decay . Mass dependent limits on λ′ are obtained in the framework of the minimal supersymmetric Standard Model. Stop quarks with masses up to can be excluded at the 95% confidence level for a Yukawa coupling of electromagnetic strength.