Hoy,
Yes, you're right,some of the horns are sounding pretty poor.
I think to create a nice sound is to sample a real hornsound,by using a sampler.Or if you are realy creative,use a synthesizer.
Than you have to play with the A.D.S.R (Attack,Decay,Sustain,Release).I remember when i had my sythesizer(JX8P)from Roland, i even created a perfect helicoptersound.
Maybe we can find some member who is willing to take time to create sounds for the different vessels.
Dont get me wrong, it takes time to create a perfect sound.It took me to create that helisound some houres,believe me.
Regards
Marc