The tonnage figures we all quote are based on enclosed volume and not really the weight, although it will obviously be higher, having 2 extra decks and being wider and a bit longer.
I did however notice that Iona seems underpowered compared to Eclipse at 61.7mw vs 67.2 me, but there is no comparable propulsion data on wikiperdia. However Eclipses top speed is 24 kts vs 21 kts, so it does seem Iona may not have the same oomph.