Yes, by Aussie and NZ design standards they have low bridgedecks. By British standards, not so low.
The basic hull
design is French - LaRouge, with modifications by Manta in lengthening the hull
- and the bridgedeck height as delivered from the factory is 24" (610mm). The original design bridgedeck height was around 30" (760mm), but that is without any of the stuff that makes it a Manta (much of which, in my opinion is worth the weight).
This clearance goes down fast when weight is added by the owners, as the narrow hulls sink an inch for every 900 or so pounds added (just filling the diesel
and water tanks
adds 1500lbs and most have a 300# dinghy
package on the davits
- down 2" just leaving the fuel
However, the bridgedeck is a continuous, arched, smooth structure with nothing sticking out of it like berth bumps, etc, and no flat surfaces at all. This mitigates pounding and wave pressure by a lot. The boat is surprisingly smooth in seas for the height of the bridgedeck. I have been on other boats with higher flat bridgedecks with bumps and ledges in them that slammed more and moved furniture around.
But it is a relatively low bridgedeck height.