donzi 28 sportsman

[wildfire007]

Can anyone please post pictures of their 28 sportsmans.need pictures for reference. what are some of the repower choices that are being considered?

[Dano]

Being a diesel guy, I think this is the only way to go unless speed is your only interest in which case you got the wrong hull. I would recommend Cummins MerCruiser Diesels 2.8 liter 200 hp or 4.2 liter 320 hp. There is some good tech info on their website.
The benefits of the diesels are much better fuel consumption, faster cruise speed and better resale. The cruise speed is faster as diesels are typically 200 rpm off their rated speed (5 -10%) where gas is ~3000-3200 rpm and rated at 4400 -4800 (30%).
I suspect the resale would be of little benefit as an old hull will probably not have very good resale in any case.
As I understand these boats would run approximately 45 mph with a pair of small blocks at 250 hp. Can anyone confirm???
My quick calculation says it would be about 49 mph with sterndrives as a result of reduced drag. If this all holds true then a pair of 200's would give about 44 mph, and 320 about 55 mph.
I believe the 200 would go in without too much modification and the 4.2 would definitely need some deck work. Stringer width is another concern. In order to maintain the original stringer width I had to set my drives at 32" which put the engines on top of one another. I glassed in one layer of 3/4" plywood to the inside of the transom to get the correct thickness.
The deck hatches will most likely need to be raised. I have seen the whole deck in the back raised a few inches. I modified my deck to combine the two engine openings into one and am building a one piece motor box which will be a rear seat and sundeck. I am maintaining the ability to walk around my motor box.
The easiest would be to remove the entire deck inner-liner from the rear hatches back and put a traditional sport boat back seat and sundeck.
If you want to stay inboard I would recommend the 2.8 200's which would probably give 40 mph (again if the assumptions above are true). You will need to mount the engines on an angle as the original gas were as the prop shafts are 27" on center and I don't know of any gas or diesel engine which you could mount without being on an angle. I would only let a very skilled mechanic install these as the u-joint angles must be equal or there will be a severe vibration.
.....Dano

[MOP]

The fellow that owns the marina where I am based is slowly refurbing a 28 Donzi and he is pretty set on going with the new Volvo diesel Dou prop I/O setups. I have another buddy with a 31 Bert SF model that put a pair of 502 with a tad over 400HP, he can not run WOT in clam water. Due to the shaft angle the boat goes fast enough to get too flat and starts to bow steer, he is considering going to Bravos jack shafted. East End Diesels owner had to de tune 315 Diamonds in another 31 Bert for the same reasons, which was very disappointing to him and his customer. I wonder if the 28 Donzi will suffer from the same issue in calm waters, something to think about before going into big bucks.

Phil

[falcon]

depends on how you will use the boat--- i would use it for offshore fishing--and would want to get the rear deck lowered(just the raer hatches)enough and remove that ugly stern rail and add some safety--it that case you would need to eliminate the v-drives and make it a straight inboard---if you look at a 28 performer--thats exactly what they did-(some say performer bought the donzi molds-some say it was an exact copy)---getting the weight to the transom is great for racing but straight inboards will make it a better fishing boat and eliminate the complexity of v-drives.

my 31 bertram has the motors placed this way and runs pretty good in the ocean.

with fresh small blocks---i doubt you can reach mid 40's---i think donzi ads were very optomistic---maybe with fresh big blocks.

there is a lot of talk of ethonal and fiberglass tanks on the bertram website---i am pretty sure donzi used monel if the tanks are original--if not or if you are planning new tanks --go with stainless---i am hearing reports that the ethonal is starting to react with aluminum as well. thats only for gas if you are planning diesel --no problem.

[falcon]

concerning 31 bertrams---there are plenty of diesels 300-330 hp on the web site---no one seems to complaining about bow steer---most of these boats are reaching 33-34 knots a wot.

there is talk of higher hp applications causing problems---most attribute to shaft angle--but i think it is also due to to much blade surface---the high torgue of the motors allows a very large 4 blade under the boat---but it is causing stern lift.

i run a very light gas boat and can regularly hit 36 kots (41 mph) with no adverse handling problems.

also there is a 440 hp yanmar diesels that was just talked about on the web site that can hit 46 mph with a full tower-not sure how it handles.

concerning shaft size---diesels would require a mininum 1 3/8 shaft--as you approach 300 hp---you should increase to 1 1/2 aquamet 22.

[J&K SHAHBAS]

I will let you know how a 28 with 502s and casale v-drives runs in about 4 months!!!! Wildfire could you email me @ jhstri@aol.com about the 28 that you referred to. I had trouble repling to you through donzi.net. Thanks