Help with '75 18 ft Seacraft project

adamcannon · #1 08-23-2009, 10:23 PM

Thank you for the input. The stern weight is one of my biggest worries. I have removed the infloor baitwell. I am thinking about putting it in the box seat in front of the console. I think the specs said the dry weight of my boat is around 1400lbs. I am taking out every piece of wood in the boat and replacing it with pinski board. It is about 1/3 of the weight of plywood and just as strong. So I would expect the over all weight of the boat would be reduced considerably. The gas tank had been replaced but who ever did it did a shotty job. All the wood over the tank was rotten and water logged. The stern was also very bad. I am also going to grind all the wood out of the gunwales and replace it with composite. The previous owner had a 100hp yamaha four stroke on it and said it did fine. I would think it would be very bad on the hole shot with that motor, but I could be wrong. Those motors I am pretty sure are over 400lbs. The bracket I am getting is positive floatation so I am hoping that will help with stern weight at least at a stand still. I was wondering if anyone had done anything with moving the gas tank forward to compensate for the motor being an extra 26" off the back of the boat. Seems like it would help but I dont want to do anything that will hurt the performance of the boat.

Bushwacker · #2 08-24-2009, 09:48 AM

With your concerns for balance and stern weight, which I agree with by the way, I would highly recommend a Hermco bracket because they have the most flotation. Don said he can make them with various setbacks . . . 18", 24", 30". The 30" is nice if you're a diver, but otherwise you could use a shorter one, especially if you pick a V-4 motor. Also if you're boating in salt water, you won't have to worry about corrosion issues with it.

adamcannon · #3 08-24-2009, 11:40 AM

Yeah I would love to have a hermco bracket. They are extremely nice. I do have some budget issues and had to order one I could afford

. One day if I ever find a good 23' seacraft I might look him up to make me one for that. I am hoping with a lighter v-4 I can get by with the cheaper aluminum bracket. I looked over all the pics on the hermco website and I like the water tight fittings for the controls and steering cables. Does anyone know where I can order those thru-bracket fittings

.

vcs · #4 08-24-2009, 04:01 PM

Here is a link to pictures of my 18 that don at hermco did for me http://hermco.net/gallery-2.htm

Bushwacker · #5 08-24-2009, 06:12 PM

Quote:

. . I looked over all the pics on the hermco website and I like the water tight fittings for the controls and steering cables. Does anyone know where I can order those thru-bracket fittings

.

If it were me I'd save some money by using balsa core instead of Penske board or whatever in the deck and put the savings in the bracket. (Balsa core works fine, but as with any cored structure, you just have to properly seal any holes in it with the drill oversize, fill with epoxy & redrill routine.)

The hydraulic steering hose fitting is a Cable Clam which is available from West Marine and other marine supply outfits. It's just a tapered round rubber plug with a tapered plastic ring on outside. Just drill the size holes needed for hoses in rubber plug and then cut the plug in half on centerline of holes. With a little silicon around the hoses, the tapered ring keeps everything in compression and water tight. I've also seen metal fittings for hydraulic hoses that go thru a bulkhead where you connect a hose on each end. Makes for a neat installation but it adds 2 more hoses and 4 more connections which are a potential leak source. Advantage is that when UV finally kills the hoses, you only have to replace 2 short hoses instead of the long ones all the way to the helm!

The fuel line/control/electrical cable rigging kit is probably available from numerous supply outfits, but I got it from Don for about $45. I like the way he rigs it down into the bracket and then into the transom inside the bracket because then you can walk across the platform w/o having to step over all that stuff. Kit includes 2 aluminum tubes, about 2" OD by about 4-6" long, and 2 flex hoses and clamps that fit over the tubes. If you're having an aluminum bracket made up, you might want to have the vertical tube welded into the bracket so it's coated or painted at same time as rest of the bracket. Also, after you put the tube thru the transom and run all the rigging thru it, fill it with silicone. It's probably below the waterline, so if you ever develop a leak in the bracket tank for whatever reason, you don't want that sinking the boat!

adamcannon · #6 08-24-2009, 07:28 PM

Thanks vcsjupiter for the link that is a very nice setup. I bet she will fly. Can you tell a huge difference in the performance of the boat while underway with the bracket? How much setback is your hermco bracket? Do you think I will need to have trim tabs on my boat for any reason?
Thanks

Thanks Bushwacker for the info. If I understand correctly I need a tube welded in for the throttle cables,wiring harness, and power cables to go thru then a sleeve goes over all of it to the motor and it secures with a clamp around the aluminum tube that is welded in. Sorry for all the questions but on this website everyone is so helpful even with my stupid questions. Thanks again.

vcs · #7 08-24-2009, 07:56 PM

Adam yes there is a huge difference in performance, i went with a 30in setback on the bracket, I went with a doelfin instead of trim tabs and it rides great.
Tony

Bushwacker · #8 08-25-2009, 01:06 AM

Quote:

. . .If I understand correctly I need a tube welded in for the throttle cables,wiring harness, and power cables to go thru then a sleeve goes over all of it to the motor and it secures with a clamp around the aluminum tube that is welded in. Sorry for all the questions but on this website everyone is so helpful even with my stupid questions. Thanks again.

Adam, like I used to tell the guys that worked for me, no such thing as a stupid question . . . only stupid mistakes!

Your understanding of the rigging tube assembly is correct, assuming you want to rig it like Don Herman does. You could just drill a hole in the bracket and secure the tube with epoxy, but if you're having one made up, seems like it would be cleaner to just have one welded in before they powdercoat or paint it. You'll still need a smaller hole for the hydraulic steering lines.

Regarding trim tabs, I use them primarily for lateral (side-to-side trim). A deep-V will tend to lean into the wind; the wind blows you off course, so when you crank in some rudder to correct, boat will roll in the direction you turn the helm. When you lay a deep-V on it's side, it's NOT a deep V anymore! When waves are coming at you at some angle off the bow, rolling the boat just a few degrees AWAY from the waves with the trim tabs increases your deadrise relative to the waves and will create a big improvement in the ride! You can do the same thing by moving gear or crew around, but the tabs are more convenient. I also use a Doelfin for fore & aft trim, and on a 25" motor on a bracket, it makes a big difference. Also if you're stern heavy, a 4 blade prop will also give you some stern lift.

Fr. Frank · #9 08-25-2009, 07:42 AM

Quote:

no such thing as a stupid question . . . only stupid mistakes!

Yeah. Usually caused by not asking questions in the 1st place.

Quote:

Regarding trim tabs, I use them primarily for lateral (side-to-side trim). A deep-V will tend to lean into the wind; the wind blows you off course, so when you crank in some rudder to correct, boat will roll in the direction you turn the helm. When you lay a deep-V on it's side, it's NOT a deep V anymore! When waves are coming at you at some angle off the bow, rolling the boat just a few degrees AWAY from the waves with the trim tabs increases your deadrise relative to the waves and will create a big improvement in the ride!

...Also if you're stern heavy, a 4 blade prop will also give you some stern lift.

Excellent advice!!