Help with '75 18 ft Seacraft project

adamcannon · #1 08-23-2009, 05:05 PM

I am just getting started on my 1975 18ft seacraft. I am competely redoing everything. New floor, stern, paint, gelcoat, and motor bracket. I will try to post some pics of the progress from start to finish. I am going back with all composite material and I ordered an aluminum bracket w/swim platform. My brother-in-law is a very experienced fiberglasser and painter but I may need some input when it comes to mounting the bracket and motor. I was wondering if a 115hp motor would be sufficient for my boat. I am closing in the stern and the bracket I ordered has a 26" offset. I'm not sure how high to mount the bracket or if I will need a 20" or 25" shaft. I have tons of questions as you might would guess. I have a t-top and leaning post that came with the boat when I bought it which I love, but I'm not sure how to position it in the boat to make it where it is not stern heavy. This is my first seacraft and I like the potter hull design. I have never ridden in one of these boats but everyone I talk to say it is by far the best mono hull boats money can buy. Any input on horse power, setup of console, and bracket mounting would be appreciated. This is a great website and look forward to talking to some of you about your trails and tribulations that may save me the headachs that I am sure alot of you have already been through and learned about the hard way. Thank you for your time.
Adam

eggsuckindog · #2 08-23-2009, 08:36 PM

I had one with a 115 inline Merc and it was fine, no T Top and on rare occastion I wish I had a bit more but it really was pretty fast - I am a gear head. Keep in mind those motors weighed in at 268 I think too, so weight is the biggest issue especially if you use the infloor baitwell. With the heavier motors today I would think about a baitwell under the leaning post. If money is no object a 115 HO Etec would be perfect as its 4 cylinder.

small45 · #3 08-23-2009, 10:20 PM

my 77 18' has an older 120 omc, and it has ample power. my 75 18' has a 150 yamaha, and it has more than ample power. i would think a newer 115 would be a good choice. especially on a bracket. i would do away with the in floor live well and build one into the front of the console. i was going to do this on my rebuild but ended up using a newer mako console with a 20something gallon live well built in. my boat rides great when it's full. i also have a 12 gallon secondary well in the transom but i mostly just use it for a trash can

adamcannon · #4 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.

adamcannon · #5 08-23-2009, 11:17 PM

http://s777.photobucket.com/albums/y...amcannon_1982/

Bushwacker · #6 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 · #7 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 · #8 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 · #9 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 · #10 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.