74’ Seacraft 23 CC Rebuild
 

So... let the “fun” begin.

My goal is to remove all wood and old foam in stringers. Rebuild transom, deck and top cap. Then refinish hull, mount outboard bracket and install twin 150’s.

Engine and stern drive are out, 900 lbs. combined weight. Console removed and deck hatches opened. Gas tank drained and removed. Most of hardware removed.

MY DILEMMA IS...
The tank measures 36” x 28” x 13.5” and holds 59 gallons of fuel @ 100% capacity. Weight of 59 gallons of fuel is approx 355 lbs. Should I move tank forward of the center console location to compensate for what I assume will be 850 lbs. of engines, plus 200 +/- lbs. of bracket hanging off the stern? I also intend to install a taller console with a T-top as well.

Any build suggestions would be greatly appreciated! Thank you in advance.

I don't think a 59 gallon tank is going to cut it. I'd look at a 85 to 100 depending on how you you your boat. Secondly, why twins? A single 250 - 300 is perfect for that hull. Here's some ideas and to go with.

http://www.classicseacraft.com/commu...ad.php?t=29137

I redid my ‘73 I/o much like you plains but with a single 300 etec —originally mine had twin 50gl tanks by opening it up under the console to the front box I was able to install a 100gl main tank and a 30gl “reserve “ plenty of fuel but up there you may not need that much for the type of fishing you do. You will love the full transom ! I made a anchor hatchin the bow as bending over and jamming anchor line just didn’t work for me . Hindsight and after fishing off Plum Isld on my brothers boat you might consider a Bow pulpit and anchor windlass god I know how manny times we pull and drop his anchor fishing the Merrimack river!

118 gal from Sunshine/Hermco bracket/Yam 300 4S. Very happy with mine. Did not move tank fwd but batteries are. I would recommend moving the tank fwd. With a 165 mile trolling trip I'll use about 2/3 of the 118 gal

Guys, thanks for the responses.

DonV - I agree that a larger tank would be better. I was actually surprised first time I put eyes on the tank. Will probably bump it up to 85-100 gallons like you suggest. I like twins for the redundancy should something go wrong. And for ability to spin boat on axis. Thanks for the link, I will be sure to check it out.

Wattaway2 - Great point regarding pulling the anchor. That's what kids are for!... BTW... glad to see you're in a warmer climate now... : )

Old'sCool - I'll be sure to keep batteries as far forward as possible too. I think with a floatation bracket I should be pretty good with retaining a good center of balance. Old engine, outdrive and battery were about 1,000 lbs. and removing wet wood in transom and engine beds will lighten rear of boat as well.

DonV - I looked at the link you shared and also the IG thread seacraftrenovation72. Great info and photos! Thank you.

A question I have is; why did you opt to entirely remove the stringers as opposed to cutting off the tops and hogging out the foam?

Estimating CG changes
 

Glosta23-
With all the changes you are considering you may want to consult my post of ESTIMATING CG SHIFT....... it is in a sticky. Original post was 9-24-16.
Best wishes on your project.

It's my brother's boat. He wanted a level deck front to back, plus he raised the deck about 1". This provided the strongest stringer grid all the way to the bow and best storage options. Also when we removed the original floor the right stringer was really messed up so we just took it all out and started new. Notice the gas tank location, it's 87 gal and we were able to position it front to back where we wanted. Good luck!!!

This is the best advice you'll read here based on your plans.

Lookup Michael Dru in Boca on Facebook. He just did a 23 with twin 150 G2's. Think he is having weight issues last post I saw. Might have corrected it with props though. Mlashb820 on here. He has a post in the for sale section. COB might be the most critical component of the rebuild. Gott get it right or you will be stuffing anchor locker with weight.

Thank you Capt. Terry. Great info and I'll be sure to do my calculations before hanging anything on the transom.

KNZ911 - Thank you. Will do!

Predicting CG changes
 

You are most welcome. I suspect others have been intimidated by the math or just decided to wing it. I made it as simple as I could- just plug your numbers in for mine. Certainly should be better than guessing. Best wishes and looking forward to results.

Having a base CG is a great starting point but you have to carefully consider all weight that will be in the boat and to compensate appropriately. The CG on a 23' boat can change drastically with things as simple as an extra person, cooler, ice, gear, livewell (empty/full) and fuel level at any given time. These factors need to be considered into the equation.

On almost all CC rebuilds the boat ends up bow lite and has to be addressed post build. I would push fuel as far foreword as possible and put the fishbox up in front of the console. Nobody is going to riding up front on a CC unless it is dead flat so count on that weight as well.

You should also consider what Don has suggested and go with a big single. Less weight, cost, less drag, 1/2 the maintenance and better performance per pony. If you are dead set on twins you should be planning on moving the whole console forward.

Not sure where the line is for the size of boats that really need twins, maybe 26'/27'+?? My opinion, with the dependability of today's outboards a 250 - 350 hp single on a 23' SeaCraft is the most efficient way to go. Now thirty, thirty five years ago dependability was not one of the outboard manufacturer's strong points.

Wish I had taken a picture last time I was at Nags Head, but, my buddy's neighbor redid a 23 cc last year and put twin 2 strokes on a bracket. Can't remember what size, but at least 175's. Anyway, he had the bottom sprayed white and the waterline at the stern is only about 16" from the cap...ON A 23!

Don, I don’t know what you’re talking about. My old girl was right at home 120 nautical offshore on the west end of the Middle Grounds as long as you had 30 jugs of extra fuel and 5 gallons of smoker oil. What could go wrong?

Yes Sir Moose......a boat's fuel tank vent hose is normally 5/8", these old V-8 OMC's were the only engines I know of that needed a 5/8" fuel line to feed the monster. Plus it was cost effective to buy 2-stroke oil by the 55 gallon drum....30 gallon drum minimum :) :)

Capt. Terry -

So... I used your formula and came up with a CG shift of 1.15 feet back towards the stern. The only variable I changed was the I/O engine to dual outboards. I haven't played with fuel tank size or location yet, or the battery location either. I am also waiting on a spec sheet from Armstrong for a dual engine bracket so I know exact weight of bracket. Would also be nice to know how bracket floatation will affect CG.

Going to dual outboards appears to only add 150 lbs. to the boat. Hopefully that 1.15' shift in CG won't adversely affect how the boat sits in the water. Or...hopefully with a little more engineering I can trim her out nicely while keeping the deck dry and the scuppers draining.

What outboards are you looking at?

150HP ETEC G2’s

Roger that. What is the cost difference to a single 300 G2? I'm sure they will perform just fine but it will be interesting to see the cost and performance differences compared to the 300.

Sorry I am responding at a disadvantage from only my cell phone while out of town. I would expect the combined CG of your 900 lb inboard and outdrive to be several inches to a foot forward of your transom. Bushwacker’s CG moved about a foot aft when he moved his ETEC 150 from his transom to a Hermco bracket. Therefore when you put two ETEC 150s on a bracket I would expect a bigger change than the 1.15’ you quoted. My 20” G1 ETEC 150 weighs 418 lb. The G2 must weigh more than that with power steering.
I agree with those recommending a large single instead of twins which I suppose opens up more space on the bracket for climbing onto when in the water.
The bracket floatation will not help your CG when underway.

Capt. Terry -

Checked my math again, and my distances from transom measurements and things seem accurate. Double checked ETEC weight as listed on Evinrude spec sheet and confirmed weight of my old engine and outdrive. Things look good.

Also received quote from Armstrong. Bracket weighs approx. 170 lbs and setback will be 30" not 36", so that should help me a little bit as well.

All interesting stuff to play around with in the hopes of getting the correct CG before actually bolting anything to the boat!! Fingers crossed...

Glostw23
 

Looks like you probably did it correctly. I will examine it again next week when I am home. And you may tinker with the calc more as you have other items to consider to minimize the cg change. Best wishes.

Just saw that Michael Dru added 300 lbs in front anchor locker to even out balance of twin 150’s. For what it is worth.

Confirming Glosta23 CG calcs
 

Glosta23-
Upon my return home I examined your cg calculation. Your use of my method and calculations appear correct. And recognizing in the CSC-world there are different opinions here are some comments:
1-Although your predicted 1.2’ cg shift aft may seem negligible, you may want to consider other ways to shift or reduce it. Bushwacker after his ETEC 150 was mounted on a Hermco bracket had to move his trailer axle 11.5” aft to maintain the original tongue weight. In addition it adversely increased his minimum plane speed from about 13 to 17-18 mph (don’t remember the exact numbers), He has plenty of posts describing the pros and cons of brackets.

2-KNZ911 mentioned it took 300# in the bow locker to balance out twin 150s. Plugging 300# and 21’ from transom in the calculation would put your cg right back where it was originally.

Best wishes and enjoy your project

Did you look into relocating the fuel tank forward shifting a lot of weight under the center console instead of behind it

Just to update a little. Michael Dru is looking to sell his twin 150's for a single 300. To much weight even with the added bow weight. I would love to have twins on mine, but it's just not the right sled for it.

KNZ -

Yes, Michael and I have messaged each other off the forum and he feels his boat will ride better with a single. Maybe I am just a contrarian but I'm still not convinced 100% and will reserve my judgement (on my boat) until I am absolutely certain which direction to go...

Each build is unique as you know and I think certain variables could potentially move the needle for me in either direction. I have friends who run both singles and twins and i hear a lot of conflicting information. Hopefully I'll make the right decision based on how I build the boat, and hopefully I won't regret the direction I choose... I do enjoy all the insight gathered from CSC though!! So much great info shared here...

Happy to see you are absorbing all info and deciding what would work best for you. Thats the only approach i believe in!!

KNZ -

There is surely no shortage of information on this site! Love seeing all the pictures and diagrams/drawings of work in progress as well as completed boats. Lots of pressure to do good work on my boat!...