Couldn’t agree more @Mitch and that would certainly be my first advice for poor performance. Unfortunately while doing extensive testing up in the frozen north we’ve over pressured the floor on the water to 1bar when the problem manifests, all to no avail unfortunately. It can perform ok going with or broadside to chop, turn into said chop and all goes pear shaped. Only cure is to trim excessively in.
More or less convinced now it’s a leg length/transom depth issue. I think the Mariner leg is probably about 10mm too short for a T38 transom. On inspection it looks perfect, dead level with keel, and on flat water av plate rides nicely visible flat and right on the water surface. Head into a bit of chop, water flow off transom disturbed and extended tabs cause such a light boat to ride just a wee bit higher....and prop loses grip. Trim down and usually grip restored. If prop was 10/15mm lower I don’t think this problem would occur. A slightly cupped prop may improve the situation.
At the moment I would be hesitant to recommend anyone mating a T38 with the new Mariner/Merc/Tohatsu 20. The Suzuki powered T38’s seem much more tolerant... be interesting to compare av plate heights and see if the Suzi sits fractionally lower. I know leg lengths vary fractionally between manufacturers.




