Hatt 34 Waterline height change

[micky]

I'm removing about 3,000 pounds from the boat, repowering from 2100 lbs Detroits to 1200 lbs Yanmars.
Also removed all the interior wood floor and the frame will be replaced with aluminum, back wall removed (wood) will be replaced with PVC also removed A LOT of wood on the interior.

How much do you think will be the difference in waterline height? 2-3 inches?

 

[Boatsb]

Not only height but the orientation will change. Your removing a lot of weight from the middle and aft sections.

Are the yanmars 1200 each or total? Same as the Detroits. Sounds heavy if its each.

 

[Avenger]

When we stripped the bottom of my 36 we could see the original waterline from when it had gas engines vs after the 3208s were installed. The change was about 6" at the bow, but there was no discernable difference at the stern.

 

[Captain Ralph]

To keep your water line and boot perfect.
Don't worry about it on first splash. You may even still be moving things around after your first splash any way.
You may even need to move some things around after your sea trials. Batteries here or there is my first example.
Then, when the running of the boat is as close to perfect to run with out tabs (very little), then lets find your water line.

I know you want it all done now and all will just be poorly guessing.
If you want that perfect water line, it's worth waiting for.

 

[Boatsb]

I've been in a few 34 hatts that were repowered. Theres not a lot of room to move things for that perfectly balance nor will the location of a 50 lb battery change the ride of a 19,000 lb boat.

Speaking of repowers I will be replacing motor mounts and towers on one. The repower was done with wood blocks. They split. The motor shifted, the dripless shaft logs did just as expected and the bilge pumps had to work overtime.

The moral of the story. Do it right the first time. Dont cheap out or make do. Custom motor mounts are not cheap but will keep everything secure and in place.

 

[micky]

Not only height but the orientation will change. Your removing a lot of weight from the middle and aft sections.

Are the yanmars 1200 each or total? Same as the Detroits. Sounds heavy if its each.

Old engines: Its each, each detroit (453t) weights 1800 dry weight plus coolant and oil, each transmission (borg warner) weights 175 without oil.

New engines:Yanmars (6lpa) weights 900 dry weight plus coolant and oil, each transmission (twin disk) weights around 300 without oil.

 

[rsmith]

When my dad repowered out 65 34 I don’t think we had to raise the boot stripe more than 2” and the weight change was considerable. We took out the 290hp Chrysler gas engines and put in 3160 cats. We also added 35gallon saddle tanks in the sides of the deck house because the STD 200 gallons was marginal for the offshore canyon runs we did at the time.

 

[34Hatt]

The first few years I owned mine I shed lots of weight with replacing with cored materials. Dash, walls. hatches and never noticed any difference.
Then I took out 504 Cummins big V-8s replaced with Cummins 330B it was about 1,400 lbs, less water line never really change I was shocked. It did how ever keel walked from 25kts and up 28.77 mph for the river rats
Then added a generator around 440 lbs no water line change but it stopped the keel walking!
When going offshore overnight I fill with fuel take a extra 42 gallons extra about 600+ quarts of Ice 4 other guys and gear 12 rods bait for overnight I see 1.5" to 2" of drop in transom and no change in the bow.
Basically what I have seen in 20 years of ownership is it takes a lot of weight for change. They weigh so much its a small percent of overall thats why when walking up the side of a 34 Hatt she doesn't lean like a typical 34'.
Should be Interesting to see your out come but as others said don't change water line until your all done which usually never happens

 

[Colwyn D]

Of limited use but my 42c rises by 2" at the stern when 250g of diesel have been used (1750lbs). Tanks are under cockpit.
Engines were changed from Cummuns 903's to 6cta's and not much of a change in waterline, 3/4" maybe.